Actual, True Malignant Melanoma:
(melanocytic neoplasm with loss of growth controls, asymmetry, irregular borders, haphazard coloration):

• NOTE¹:
  • CLINICAL, PHYSICAL-EXAM detection:
    • 50% are patient-discovered.
    • be concerned if: a new lesion appears (or you note changes in size, shape, color, or sensation [it now burns, is painful, bleeds, or itches] of a pre-existing mole)...while melanomas are usually pigmented, they may not be (then called amelanotic melanoma).
    • if you REALLY want to catch the melanoma early, you should undergo total-body exam (these exams find 6.4 times the melanomas than partial exams)¹.
    • PHOTO-RECORDING for serial COMPARISON: AND, if you have lots of nevi, the new "MoleMapCDT" System of tracking your moles may be at a site near you (my son works with the Columbia, S. C. partner of the inventor, Duke U. dermatologist & researcher, James Grichnik, M. D.). A medical photographer makes 33 standard body site digital photo images which are transferred to a CD by Digital Derm (of Columbia, S. C.); and one CD goes to the patient and one to his/her participating doctor. Over time, changes in moles can be discerned by baseline comparison with the CD. Dr. Grichnik tracked 526 patients with this system for an average of 2.4 years, and they had an average of 1.5 biopsies per patient per year (a similar set of patients are said to average 6 biopsies per year by conventional follow-up exams). Costs about $400 as of July 2004.
  • history: is there any family history of melanoma?...previous in this patient?
  • risk: persons with lots of moles who sunburn easily are at higher risk (fair-skinned, red heads more susceptible & dark skinned rarely have melanoma); however the ALM & MLM varieties are equally present in both light & dark skinned persons.
  • ABCDE check-list:
    1. A= asymmetry: if you imagine dividing the mole in half, the halves are clearly not equal.
    2. B=border: when the border is irregular.
    3. C=color: when more than one pigment color is present.
    4. D=diameter: when the diameter is greater than 6 mm. (about 3/8 of an inch) (but there are definite instances of melanoma smaller than 6mm.).
    5. E=elevation & evolution: the degree of macularity (can't feel a "macule"...has it changed in size, color, "feel", shape, itch/sting ?).
• basic melanoma diagnostic criteria, click HERE.
• caveat...a pathologist must always think of MELANOMA: "A variety of cytomorphological features, architectural patterns and stromal changes may be observed in malignant melanomas. Hence, melanomas may mimic carcinomas, sarcomas, benign stromal tumors, lymphomas, plasmacytomas and germ cell tumors. Melanomas may be composed of large pleomorphic cells, small cells, spindle cells and may contain clear, signet-ring, pseudolipoblastic, rhabdoid, plasmacytoid or balloon cells. Various inclusions and phagocytosed material may be present in their cytoplasm. Nuclei may show bi- or multi-nucleation, lobation, inclusions, grooving and angulation. Architectural variations include fasciculation, whorling, nesting, trabeculation, pseudoglandular/pseudopapillary/pseudofollicular, pseudorosetting and angiocentric patterns. Myxoid or desmoplastic changes and very rarely pseudoangiosarcomatous change, granulomatous inflammation or osteoclastic giant cell response may be seen in the stroma. The stromal blood vessels may exhibit a hemangiopericytomatous pattern, proliferation of glomeruloid blood vessels and perivascular hyalinization. Occasionally, differentiation to nonmelanocytic structures (Schwannian, fibro-/myofibroblastic, osteocartilaginous, smooth muscle, rhabdomyoblastic, ganglionic and ganglioneuroblastic) may be observed. Typically melanomas are S100 protein, NKIC3, HMB-45, Melan-A and tyrosinase positive but some melanomas may exhibit an aberrant immunophenotype and may express cytokeratins, desmin, smooth muscle actin, KP1 (CD68), CEA, EMA and VS38. Very rarely, neurofilament protein and GFAP positivity may be seen¹¹." In very rare instances, it might even take electron microscopy to make a melanoma diagnosis [S-05-10434].

NODE CAPSULE PRIMARY: On finding a "positive" sentinel lymph node (SLN), the pathologist must be careful not to interpret small node capsule melanocytic nevi (amitotic and low Ki67) as metastatic melanoma. Likewise, it is possible that a melanoma initially diagnosed in a pathological node is a capsular nevus primary [L08-3623] if the previous history is totally negative and the patient is also currently negative for a primary melanoma of skin or mucosa.

• "early"abnormal junctional melanocyte changes: when...always after proper step-sectioning of the biopsy...the histological changes of the lesion seem to be not clearly "just" a nevus or dysplastic nevus, but not enough atypical abnormality for a clean and confident diagnosis of at least MIS (be sure to find out if the lesion might be a recurrent nevus with atypia, see below), there are various ways to express your diagnosis: "proliferation of atypical melanocytes confined to epidermal and adnexal epithelium" ^{4, AB Ackerman}, "atypical intraepidermal melanocytic proliferation"^{4, AM Rywlin} [S-07-11616], "atypical intraepidermal melanocytic hyperplasia"; or, "(MIN) melanocytic intraepidermal neoplasia"^{4 GW delJunco} [S-03-4750]; "severe melanocytic dysplasia"; "severely dysplastic junctional nevus" [S-03-5197; S-05-9854]; "severely dysplastic lentigenous atypical junctional nevus"  [S-02-3559; S-02-5003, S-02-6545, S-02-9283, S-04-8009, S-04-11174; S-05-715]; "atypical junctional melanocytic lesion" (when only a small punch biopsy of a larger clinical lesion)  [S-05-9561], "Clark's nevus, compound type, with unusual features" [S-04-6726, 17 y/o male; S-04-7604 40 y/o male]; "dysplastic compound nevus with atypical junctional component" [S-05-929], "acral junctional nevus with unusual features" [S-02-12957]; "recurrent compound nevus with atypical junctional component suggesting evolution into MIS" [S-05-8603]; "dysplastic compound nevus with balloon-cell atypical junctional component" [S-05-10621]; "Clark's (dysplastic) nevus, compound lentigenous type"[S-05-9958]; & I believe this could encompass what some call "lentigenous melanoma"...see below...when the atypia is not MIS-like, below.

Evolving MIS in a lichenoid inflammatory reaction can be a real problem [S-02-6669], especially if most of the melanocytes have been eliminated by a halo reaction. And, one can have other lesions with a combination of severe dysplasia of intraepidermal component of a compound nevus [S-02-11705].

• melanoma in-situ (MIS; melanoma CIS) [radial, non-tumorigenic state/stage]:
  • histo-morphology: increased numbers of enlarged/atypical melanocytes which lose "territorial boundaries" and begin to crowd⁵ and be confluent¹⁵; atypicalities include nuclear enlargement & pleomorphism & at least a hyperchromatic cell/nucleus or two; non-orderly cyto-histological increase in cells; neg. for invasion [S-02-841; S-02-6977 in dyspl. CN;S-03-1609; S-04-2307 in CN; S-05-1994 assoc. /w tiny CN] . If one feels inclined to do so, one can express/diagnose MIS but give parameters were one to consider the lesion Clark II [S-03-16189] in cases where one feels that pathologists might likely have divided opinions as to MIS vs. early level II.
  • synonyms: MIS & the above less definite phases were addressed by Allen in 1953 by the term "active junctional nevus"; melanosis circumscripta preblastomatosa Dubreuilh; Hutchinson's melanotic freckle, pagetoid melanocytic proliferation; melanocytic intra-epithelial proliferation; melanocytic intra-epithelial neoplasia; intraepidermal melanoma; atypical melanocytic hyperplasia; severe melanocytic dysplasia; lentigo maligna¹⁴.
    1. lentigo maligna (LM)/lentigo-maligna melanoma (LMM): highly epidemiologically related to sun exposure; & likely evolving from lentigo senilis⁵; some prefer that LM=MIS and LMM indicates LM with invasion⁷; when lesion is of severely sun-damaged skin of the upper body, it is LM/LMM (they are the same⁴); epidermis usually atrophic and not much upward scatter.
    2. when lesion is of trunk or lower body, it is MIS.
    3. & I believe this could encompass what some call "lentigenous melanoma"...see below...when the atypia is not MIS-like, below.
  • warning!: always carefully look for any evidence of underlying sparsely spindled cells of desmoplastic or neurotropic melanoma in HF, LM, or LMM.
  • warning!: if any "regressive change" (papillary dermal fibroplasia, melanophages, and some lymphocytes), it implies (but does not prove) that there has been host autoimmune halo destruction of some focal microinvasion (therefore the prognosis is "guarded"...rather than MIS cured) [S-04-4928].
  • Hutchinson's freckle⁵ (HF): a (usually facial) lesion of increased highly dendritic junctional melanocytes (rarely associated with lentigenous basal budding) which can evolve into LM/LMM in a chronic, enlarging pigmentation lesion of an elderly person. Somewhere between HF & LM one might find "lentigenous dysplastic nevus in the elderly" [S-02-11324].
• micro-invasive melanoma (radial, non-tumorigenic stage) is a term applicable to all except nodular melanoma: a sort of "quantitative oncopathology" term indicating slight & focal invasion (which might be Breslow 0.25 or thinner) [S-02-4801; S-02-7483; S-02-8647, S-02-14737].
  • inflammatory marker: a band of subepithelial chronic inflammatory cells is typical eye-catching marker⁷ [s-00-5646, S-01-9340, S-02-14737, S-03-1032A].
  • IHC help: MART-1 or pan-melanoma may be needed to spot the microinvasive component [S-02-8647].
  • cytology clues: inttra-epidermal & dermal cells similar & no dermal mitoses^{7, 15} [melanoma histology and prognostic measures].
• "hedge" category: melanocytic proliferations involving dermis..."atypical Spitz nevus¹³" (see below), "dysplastic Spitz nevus", "atypical melanocytic proliferation¹³", & "melanocytoma" (this is Dr. Mihm's category for borderline tumors such as pigmented epithelioid melanocytoma [PEM] & cutaneous neurocristic hamartoma/malignant neurocristic tumor [CNH])¹². "Atypical compound proliferation of melanocytes, favor Clark's nevus, compound type with atypical features" [odd, worrisomehistology plus Ki67 labeling of 15-20%...S08-12327]. "Hedge lesions" should be totally removed with a thin, clear margin¹³ & a wider margin if a worrisome hedge. Even atypical lesions that one is sure are benign can also be conservatively excised...just to be safe [S-06-14471].

In sorting through the melanoma variants below, remember that your first glance at the histology of an unknown might bring to mind a specific variety. But, close scrutiny is convincing that it is not so. A way to handle this is to give the true type, followed by "with___features". Example, "superficial spreading malignant melanoma with spitzoid features". Unless there is a known important significance to certain features, it is probaly best to keep these descriptive sayings in the microscopic section of the report and let the more simple actual basic diagnosis stand for the case diagnosis: SSMM.

• first melanoma type, SSMM..."superficial spreading malignant melanoma" (radial, then vertical growth):
  • some general SSMM points:
    • histology: asymmetry of lesion and size usually >3 mm; extensive scattering of cell nests and single cells (pagetoid spread) within the epidermis (can see some central scatter in the center...not the periphery...of dysplastic nevi) and adnexal epithelia, these cells usually having abundant cytoplasm with fine melanin [S-02-15720].
    • intraepidermal component: exceeds in width the dermal component & does not have features of LM or ALM.
    • thickness &/or nodularity:
      • very thin (Clark level II, Breslow thickness <0.37mm)...[S-04-14886] (also, see microinvasive, above).
      • thin (Breslow thickness < 0.76mm) (AJCC pT1).
      • medium (Breslow thickness >0.75-1.50mm) (AJCC pT2).
      • thick (Clark levels III-IV, Breslow thickness >1.50 & <3.0mm) (AJCC pT3a).
      • thicker (Breslow thickness >3.0-4.0mm) (AJCC pT3b).
      • thickest (>4.0mm &/or Clark V &/or satellites within 2cm. of primary.
      • having a nodule in an SSMM does not make it a nodular melanoma.
• SSMM variants:
  • minimal deviation melanoma: "borderline melanoma", "nevoid melanoma"...the pathologist is barely able to "get to" a melanoma diagnosis & is expressing the lack of straight-forward criteria...is suggesting that capable pathologists reviewing the case would likely disagree between melanoma & "less than melanoma".
  • spitzoid malignant melanoma: a lesion with above SSMM melanoma features that otherwise resembles a Spitz nevus...mostly due to the acanthosis (differential diagnosis chart)& maybe clefting. "Spitzian melanoma"...in young age group especially, has also been called¹³ "spindle cell and epithelioid cell nevi with atypia and metastases", "atypical Spitz nevus/tumor", "severely atypical superficial compound Spitz tumor", "severely atypical Spitzian proliferation", "malignant melanoma of the special spitzoid type", "malignant Spitz nevus", "metastasizing Spitz nevus/tumor", "atypical pigmented and spindle cell nevus", "atypical dermal melanocytic lesion with features of Spitz nevus" (spitzoid melanoma). But, we must remember that, in the final analysis, any melanocytic lesion that metastasizes is a melanoma¹³! [S-03-1311 13 y/o female; S-04-4520 favor Spitz;? S-04-10095; S-05-5955; S07-2577]. Can be dermal based & no epidermal connection.
  • desmoplastic (DM) &/or neurotropic melanoma (NM): usually in sun-damaged skin and beneath a HF-like to MIS proliferation & can be very subtle or can look clinically¹² like a blue nevus, dermatofibroma, or even a cyst. DM often not Mart-1 or HMB45 pos. & only 98% S100 pos. but almost 100% NSE pos¹⁹ . See spindled celled melanoma, below. Can be dermal based & no epidermal connection.

  Neurotropism: perineural space invasion (PSI) is an extremely important feature to discern...in melanoma or any other malignancy! Even if asymptomatic, coincidental, and contiguous (just within the zone of 1.0cm surrounding the tumor...[L07-132]), the local recurrence rate in melanoma with neurotropism is about 50%; 25% metastasize distantly. Failing being able to have a 2cm or more wide local excision margin around melanomas with neurotropism, one needs to consider adjuvant radiation as a way to "clear additional margins; even more extensive radiation needed if cannot surgically exterpate tumor or have other evidence of deep neurotropism-induced neuropathy^{16, 17, 18}.

  • verrucous malignant melanoma: acanthosis beyond Spitzoid to actual verrucous acanthosis.
  • balloon-cell melanoma: large pale cells with central atypical nuclei³.
  • vesicobullous melanoma: confluent intraepidermal replacement of basal cells by malignant melanocytes⁴.
  • signet ring cell melanoma: the malignant cells have a signet cytology.
  • nevoid melanoma: [DDX CRITERIA HERE] a melanoma with low power architecture of compound or intradermal melanocytic nevus; can be HMB45 negative; small cell type looks like nevus & large cell type like a Spitz; cytology of melanoma (careful...it could be an AFX [S-03-12071]) with increased Ki67 proliferation; and I think that they can be quite deceptive [S-05-113; S06-16050].(some say it is melanoma in pre-existing nevus..."nevoid melanoma") (be careful not to over-estimate thickness or Clark level): I have heard Bernie Ackerman say that this is a term used when a melanoma was initially signed out as a nevus; some use this term for a melanoma with no detectable connection to the epidermis¹⁰ [S-95-953, S-96-5931];...but, one may need IHC to appreciate the intraepidermal component; whether develops in pre-existing congenital or acquired nevus, some would call it "nevoid"...arising within a nevus..."melanoma"; "nevoid melanoma": when transition between the benign & malignant components are very subtle and uncertain⁸; some use the term as a synonym for "minimal deviation melanoma"¹⁵.

  • lentigenous melanoma: a very slow growing lesion with retiform epidermal hyperplasia and closely packed...but faintly pagetoid-pattern (non-theque)...junctional melanocytes, maybe with slight upward scatter & cytological atypia²¹ (I dont think we ought to call these "melanoma"...see early atypia, above, unless MIS-like).
  • spindle cell melanoma: is the generic, descriptive category & if plumply spindled, some resemblance to Spitz because of the spindled cellularity, but which is more horizontal [S-04-10739, S08-3385]. When very thinly spindled, one may call it desmoplastic melanoma (terms varying as between fibrous blue nevus & cellular blue nevus...dermatofibroma & cellular dermatofibroma). Can be dermal based & no epidermal connection.
  • myxoid melanoma: the associated stroma can be so prominently myxoid as to simulate myxoid liposarcoma or myxoid schwannoma³.
  • melanoma with osteocartilaginous foci:³.
  • osteosarcomatous melanoma:³.
  • hemangiopericytoid melanoma:
  • micronodular melanoma:
  • sarcomatoid melanoma:
  • pleomorphic melanoma:
  • rhabdoid melanoma:
  • pseudopapillary melanoma:
  • adenoid melanoma:
  • small cell melanoma: usually arises in congenital nevus & looks Merkel-cell like.

Circumscribed Pigmented Lesions Without Increased Melanocytes:

• freckle (ephilis): sun-induced or PUVA-induced pigmented macules; never truly "black"³ but often with an occasional enlarged melanocyte⁵ amongst darker basal cells; simple/simplex freckles are small (1-5 mm); sunburn/actinic freckles are larger.
• melanosis (melanotic macule) of the vulva: darkly pigmented patches...basal hyperpigmentation.
• vulvar lentigo:
• melanotic oral macule (s): varies location from lip through oral mucosa
  • sporadic & isolated lesions: [S-05-6260A].
  • Peutz-Jeghers syndrome with oral and perioral facial pigment macules and intestinal polyps and maybe ovarian tumor (SCTAT tumor).
• lentigo simplex: lentigenous rete elongation and basal hyperpigmentation...non-actinic sites. Brown to black. Don't become melanocytic nevi.
• "liver spot" or age spot (solar lentigo; actinic lentigo; lentigo senilis): rete elongation and basal hyperpigmentation; these may progress into a melanocytic nevus. Brown to black.
• (thought to arise from actinic lentigo ) reticulated (adenoid) seborrheic keratosis³.
• dermatosis papulosa nigra: 35% of adult African Americans have circumscribed papules of face and neck which are hyperpigmented and have the morphology of a pigmented seborrheic keratosis.
• segmental pigmentation anomaly (SPA):
  • cafe-au-lait ("coffee with milk") macules (CALMs): most people with these DO NOT have neurofibromatosis but 90% of people with neurofibromatosis have them...sunlight independent, sharply defined lesions of several millimeter to multiple centimeter size³; basal cells hyperpigmented & maybe an increase in junctional melanocytes.
  • segmental pigmentary disorder (SPD) simplex: looks a lot like a large cafe-au-lait macule...hyperpigmented basal cells only...doesn't photograph as well as CALMs. Can also be a hypopigmented lesion.
  • nevoid hypermelanosis: like SPD but not dermatomal.
• melanotic patches of Albright's syndrome: usually large and light brown spots with serrated or angular margins & hairs within it may be darker.
• pigmented dermatofibroma.
• Becker's nevus (nevus spilus tardus or pigmented hairy nevus): large spot with sharp but highly irregular border, the hairs of which (hairiness coming later) become coarser and darker³.
• localized post-inflammatory hyperpigmentation: pigment in melanophages.
  • ***always think of burned-out, halo reaction or regression of a nevus/melanoma***.
  • not otherwise specified.
  • partially lichenoid actinic keratoses with lots of melanophages [S-05-2743].
  • lichenoid, LP-like keratoses (usually not on sun-exposed skin).
  • fixed-drug-eruption induced.
  • Berloque pigmentation: perfume/cologne phototoxicity-induced.
  • erythema ab igne: prolonged exposure of the skin to radiant heat induces a reticulated pattern of increased melanogenesis.
• notalgia paresthetica: often associated with a pigment patch, this is a situation of unilateral sensory neuropathy usually affecting the infrascapular area with pruritis, hyperalgesia (heightened/excessive sensitivity to pain), burning pain, and/or tenderness [S-02-6162]. May see slight acanthosis and some melanophages (pigment incontinence) and even some macular amyloidosis on biopsy [S-05-12000].
• large cell acanthoma: actinic lentigo with large nuclei of keratinocytes³.
• chloasma (melasma): macular, patchy facial hyperpigmentation³.
• urticaria pigmentosa: hyperpigmented skin macules, papules and nodules that wheal when rubbed, the pigmented lesions often being in association with other yellow, red , and red-tan lesions; pigment is even-colored but margins faded and not sharp. There is a widespread variant called telangiectasia macularis eruptiva perstans³.
• macular amyloidosis³.
• Dowling-Degos anomaly (reticulated pigment anomaly of body folds): axillae & groin folds first....then trunk, arms, thighs, and face³.
• hemosiderin: previous hemorrhage site.
• partially or totally infarcted (irritated) skin tag.
• partially or totally thrombosed hemangioma.
• pigmented keratoses: seborrheic, actinic or solar keratosis or PMK; a very highly pigmented SK has the old name melanoacanthoma of Bloch, type II5.
• pigmented Bowen's disease.
• Bowenoid papulosis of the genitalia: condyloma acuminata like clinical papules having bowenoid histology, often pigmented.
• pigmented squamous cell carcinoma [S-02-2539].
• pigmented keratoacanthoma.
• pigmented basal cell carcinoma (BCC) [S-01-2914; S-01-9804].
• acquired localized ochronosis (ALO): microscopically abnormal...yellowish to orange...colored deposits or elastic fibers; chloasma-like hyperpigmentation related to hydroquinone-containing skin bleaches³. To be sure patient does not have the systemic metabolic defect, alkalinize a fresh urine sample and urine will blacken if systemic disease; no such change with acquired localized cases [S-06-7611; S-07-3037].
• irritated (contains hemorrhage/necrotic dots) nonpigmented keratoses: seborrheic keratosis, actinic keratosis, or premalignant keratosis.
• glomus tumor [S-04-8057].
• tattoo: amalgam tattoo of oral mucosa; skin injury & foreign pigment deposit.
• drug-induced pigmentation: (minocyclin, chloroquin, ant psychotics, silver) pan dermal perivascular & interstitial pigment.
• angiokeratoma³.
• dermatofibroma.
• apocrine or eccrine hydrocystoma.
• old "blood blister": traumatic hemorrhage beneath stratum corneum or epidermis.

Pigmented Lesions With Increased Melanocytes:

In sorting through the entities below, remember that your first glance at the histology of an unknown might bring to mind a specific entity. But, close scrutiny is convincing that it is another entity. A way to handle this is to give the true diagnosis, followed by "with___features". Example, "dysplastic compound nevus with pigmented spindle cell features" [S-06-14471].

• lentigo simplex: not any predilection to sun-exposed skin; no increase to increased basal melanocytes (not in clusters/thymus) in a lentigenous epidermis with basal keratinocyte hyperpigmentation .
  • generalized lentigenous syndrome:
    • may indicate underlying developmental cardiac abnormalities³.
    • Xeroderma pigmentosum³.
  • Peutz-Jeghers: periorificial and acral lesions³.
  • Centro facial lesions associated with CNS abnormalities³.
• melanoacanthoma of Bloch, type I: a lesion of keratinocyte thickening with large intraepidermal dendritic melanocytes mixed in which contain nearly all of the pigment⁵.
• acquired melanocytic nevi (grouped collections of melanocytes):
  • nevus incipiens: features between lentigo simplex and JAN (jentigo)⁵.
  • junctional (JAN): basal melanocytes begin to form nests; when the lesion is histologically complicated by obscuring host inflammation (halo nevus reaction), the IHC stain for MART-1 can help discern the melanocytic pattern [S-02-567]; watch out for junctional atypicalities in "recurrent nevi" [S-05-8603].
  • "ink dot" nevus: clinically intensely dark & sharply circumscribed macular to barely raised lesion varying from a lentigo to early compound nevus.
  • intradermal (IN): dermal-only melanocytic groups.
  • compound (CN): junctional plus dermal.
  • spitzoid (IN or CN): IN/CN with some significant DDX features of Spitz but falling short of that diagnosis [S-05-8275A]; when a mixed nevus of junctional dysplastic melanocytic nevus and dermal epithelioid Spitz nevus it can be very problematic [S07-8314].
  • neuronevus of Masson: IN with neuroid features (be sure not neurofibroma).
  • balloon cell nevus (compound or intradermal): ballooned cells with normal nuclei³.
  • acral, aural, flexural & genital nevi: these nevi typically have large, irregularly shaped and irregularly positioned nests that may be confluent along the dermo-epidermal junction. There may be clefting between the junctional melanocytic nests and the underlying dermis and limited "pagetoid" scatter of melanocytes. Melanocytes within nests may be separated from each other giving a "dyscohesive" appearance. The junctional and most superficial dermal melanocytes may be large, with abundant pale cytoplasm [vulvar S-05-8367B].
• congenital melanocytic nevi
  (same distributions as acquired, but often larger):
  • histology markers³:
    • breadth >10 mm.
    • cells in a horizontal band in a thickened papillary dermis.
    • cells around and within adnexal components and/or along vessels.
    • splaying of nevus cells as solitary units between reticular dermal collagen.
  • smaller, intermediate, and,
  • giant (garment) types: "bathing-trunk nevus"; tierfellnaevus (German for "looks like an animal pelt")⁵.
  • proliferative dermal lesion of congenital nevus.
  • familial widespread melanopathy with gigantic melanocytes³.
  • congenital speckled lentigenous nevus (nevus spilus)³.
  • dermal spindled (& dendritic) melanocytoses^3,12: blue-gray color,
    1. blue nevus of Jadassohn-Tieche
       (only very rarely congenital¹²):
       • common BN: domed lesion
         1. clinical variants: agminated (a zone of skin containing multiple lesions); eruptive; plaque-like; linear; targetoid; amelanotic/hypomelanotic.
         2. histology: spindled, dendritics plus fibrosis plus some melanocytes; almost never mitosis¹².
            • dendritic type.
            • spindle-cell fascicular type.
            • spindle-cell sclerotic or sclerosing type: central sclerotic area.
            • hypercellular BN: areas of increased nuclei.
            • BN with atypia: rare & has focal nuclear pleomorphism & hyperchromia¹².
            • cellular BN (CBN)¹²: can be large & deep; & BN areas admixed with expansile, demarcated cellular nodules...rarely an "infiltrative" border [S-05-8492]. Can be mitotic but rarely more than 2/mm².
            • atypical cellular BN¹²: may include size >5CM, mitotic up to 3-4/mm², nuclear pleomorphism, and very deep.
            • epithelioid BN¹²: 1st described in Carney complex patients; spindled BN-like cells plus heavily pigmented epithelioid cells plus large epithelioid cells. No reports of node mets.
            • malignant blue nevus (MBN): spindled or epithelioid melanoma...using common melanoma criteria...in a BN or site of previously removed BN.
            • animal type melanoma: heavily pigmented mixture of spindled & epithelioid cells.
    2. Mongolian spots: sacral most common and are present at birth or shortly thereafter and usually have disappeared after teen years³
    3. nevus of Ota: trigeminal nerve distribution skin³.
    4. nevus of Ito: shoulder girdle predilection³.
• combined nevus: example, blue nevusr plus compound acquired³.
• recurrent (incompletely excised) melanocytic nevi (often broader and asymmetrical)³; can have some atypical cells.
• halo nevus (Sutton's nevus; Meyerson's nevus; leukoderma acquisitum centrifugum): melanocytic nevus with an acquired surrounding zone of hypopigmentation (cell-mediated "regression")³; can have some atypical melanocytes.
• deep-penetrating nevus (DPN); plexiform spindle cell nevus: a deep, wedge-shaped type of "top heavy" symmetrical (especially with respect to any junctional component's relationship to intradermal component) nevus with apex in deep dermis to superficial subcutis; composed of admixture of melanophages and ovoid &/or spindled melanocytes with abundant pale cytoplasm & and may have a little junctional component; may be a type of blue nevus²; atypical DPN has mitoses [S-03-12071][DPN-like melanoma S-03-13468].
• Spitz nevus (1984...Dr. Sophie Spitz): typically & classically an acquired childhood or young adult²⁰ amelanotic lesion (if a rare congenital type, usually agminated or systematized) of large spindle and/or epithelioid cells...can have pigmented variant; hyperkeratosis & hypergranulosis of the irregularly hyperplastic epidermal component; epidermo-melanocytic clefts; Kamino bodies; large nuclei in oval/spindled/round/polygonal shaped cells in elongated, often vertical nests; some epidermal scattering; mitotic figures especially in upper portions; may have many large multinucleated cells³; some cases have minimal criteria except the superficial large epithelioid cells [spindled Spitz vs. melanoma S-04-10095; minimal Spitz s-05-7430] Some have DDX concerns (differential diagnosis chart) for melanoma but fall short and are Spitz in a growing phase: atypical Spitz nevus [S-05-7599]. Atypical Spitz nevus is a Spitz with dermoscopic and histologic asymmetry²⁰.
• sarcoid-like Spitz nevus: an intradermal variant; cells & arrangement look remarkably like epithelioid histiocytes³.
• desmoplastic Spitz: dermatofibroma look-alike³.
• Reed nevus²⁰: dermoscopic pattern is starburst.
• pigmented spindle cell tumor of Reed (PSCN...1975): peak incidence in 3rd decade & 95% are on trunk & extremeties; typically a dark, symmetric, and sharply circumscribed lesion of elongated nests of spindle-shaped and dendritic melanocytes predominately as nests with vertical axes; in an epidermis composed of heavily pigmented keratinocytes (a Spitz varient)³[S-02-560; S-03-9285]. Or, it might be a dysplastic CN with PSCN features [S-06-14471].
• dysplastic nevus (Clark's nevus)...junctional or compound.
• nevus of genital skin or mucosa: epidermal melanocytic nests often quite variable and individual cells can vary³.
• varicose capillaries or venous lakes...sun-exposed sites (especially if thrombosed)³.

[melanoma diagnostic criteria] [skin diseases index]
[melanoma prognostic parameters defined]

References:

1. Whited & Grichnik, The Rational Clinical Examination: Does This Patient have a Mole or a Melanoma?, JAMA 279(9):696-701, 1998
2. Maize JC, et. al., Cutaneous Pathology, 1998 [textbook, WRA's office]
3. Maize JC, Ackerman AB, Pigmented Lesions of The Skin [text], 1987 (EJM's office)
4. Malignant Melanoma and Other Melanocytic Neoplasms, Ackerman AB, editor, The American Journal of Dermatopathology, supplement, vol. 6, Summer of 1984.
5. Pinkus & Mehregan, A Guide to Dermatohistopathology, 2nd Ed., 1976 (EBS's office).
6. Murphy GF, Dermatopathology..., [text] 1995 (EBS's office )
7. AFIP fascicle on Pigmented Tumors
8. Relevance of Vertical Growth Pattern in Thin Level II Cutaneous Superficial Spreading Melanomas, Lefevre M et. al., A. J. Surg. Path. 27(6):717-724, 2003.
9. Pitfalls in the Diagnosis of Malignant Melanoma: findings of a Risk Management Panel Study, Troxel DB, AJ Surg. Path 27(9):1278-1282.
10. Human Path. Feb. 1995.
11. Banerjee SS, Harris M., " Morphological and immunophenotypic variations in malignant melanoma", Department of Histopathology, Christie Hospital, Manchester, UK., Histopathology. 2000 May;36(5):387-402.
12. Zembwicz A & Mihm MC, Dermal Dendritic Melanocytic Proliferations: An Update, Histopathology 45(5):433-451, 11/2004.(EBS's office)
13. Mones JM & Ackerman AB, Atypical Spitz's Nevus...A Critique in Historical Perspective of Six Concepts Flawed Fatally, 115 pages, 2004. (EBS's office).
14. Ackerman AB, A Philosophy of Practice of Surgical Pathology: Dermatopathology as a Model, Ardor Scribendi, Ltd., 1999, 470 pages.
15. McKee, Calonje, & Granter, 2 vol. text, Pathology of The Skin...
16. Newlin HE, et al, U. of Florida, "Neurotropic Melanoma of the Head and Neck With Clinical Perineural Invasion", Am. J. Clin. Oncology 28(4):399-402, August 2005.
17. Stevens G & McKay MJ, Australia & New Zealand, "Dispelling the Myths Surrounding Radiotherapy for Treatment of Cutaneous Melanoma", http//:oncology.thelancet.com vol 7, pages 575-583, July 2006.
18. Baer SC, et al, Texas & Pennsylvania, ""Desmoplasia and Neurotropism: Prognostic Variables in Patients with Stage I Melanoma", Cancer 76(11):2242-2247, 1 Dec. 1995.
19. Maize or other expert consultant pearls.
20. Archives of Derm, 141(11):1373-77, Nov. 2005.
21. Ferra G, et. al., "Lentigenous melanoma: a distinctive clinicopathological entity ", Histopathology 52(4):523-525, March 2008.