Pathology Associates Of Lexington, P.A.

Carcinoma...adnexal: IHC.

Because some adnexal skin tumors behave more aggressively than common SCCs and BCCs, it may be worth determining whether an SCC with cytoplasmic vacuolation is really a keratinized sebaceous carcinoma or not. [SCC vs. BCC is an H&E effort] The adnexal cancers especially come to mind when a proliferation is encountered which (1) does not clearly attach to the epidermis; and/or, is less than "well differentiated"...and (2) they locally recurr & metastasize more readily than SCC or BCC (need wide local excision and may be candidates for sentinel lymph node biopsy). (3) Always search for perineural space invasion (neurotropism) because of the implied need for local adjuvant radiation to cover for the fact that wide to extra-wide margins may not be surgically possible. Below is an outline especially keyed toward IHC differential information of skin cancers and mimics.

IHC DDX here: Table

EPITHELIAL TUMORS

Ber-EP4: + basal cell ca; - sq. cell ca

(overlap in basosquamous cell ca)

also stains follicles and follicular neoplasms

EMA: + sebaceous ca, +epithelioid sarcoma, + eccrine

Negative in stratified sq. epith. & SCC

(in one study 85% of SCC did stain) (BCC negative)

AE1/AE3: + squamous cell ca

K903: + squamous cell ca

S100: + eccrine²

MELANOCYTIC TUMORS

S100: Melanocytes, Langerhans cells, lipocytes

HMB-45: Activated melanocytes, melanoma, Spitz nevi

SPINDLE CELL (vimentin positive) TUMORS

CD31: Blood vessels

CD34: Blood vessels, dermal dendrocytes, DFSP cells [LMC-03-6618]

Desmin: Skeletal and smooth muscle

Factor XIIIa: Dermal dendrocytes

MSA: sm. muscle

GLANDULAR NEOPLASMS

CAM 5.2 Neg epidermis or SCC

Adenocarcinoma, apocrine and eccrine

Ducts and neoplasms, some sebac. ca.; some BCCs

CK-7: Adenocarcinoma, Paget’s disease cells

CEA: Adenocarcinoma, eccrine and apocrine ducts

and Paget’s

Will not distinguish between 1^o adnexal

neoplasms and metastatic tumors

GCDFP-15: Apocrine glands specific & sensitive

NEUROENDOCRINE

Merkel cell ca: TTF1 pos. if met from lung & primary of skin is negative.

CYTOKERATINS

Keratinocytes

1 and 10/11 - differentiated keratinocytes

2 plus 10/11 - palms & soles (acral)

5 and 14/15 - basal layer of epidermis

6 and 16/17 - disorders of ↑ proliferation keratinocytes

Hair follicle

Infundibulum - similar to epidermis

Isthmus - CK5/CK6, CK14, CK17, CK19

Internal root sheath - CK4, CK18

IHC SUMMARY:

Apocrine and eccrine ducts are identical and cannot be distinguished immunohistochemically (but if GCDFP-15 pos = apocrine).

Intraepidermal and dermal ducts:

CK10

CK14/15

CK16

CK19

Secretory glands:

AE1

CAM 5.2 (CK 8/18)

EMA

Sebaceous glands:

Oil red O+ (frozen section)

Leu-M1 pos.

Differential Notes:

Eccrine - stronger staining for CEA vs. apocrine; if S100+ is eccrine.

Apocrine - stronger staining with GCDFP-15

Eccrine carcinomas: CK+, EMA+, CEA+, S100+,GCDFP-15-, HMB45-

Apocrine carcinomas: CK+, EMA+, CEA+, S100-, GCDFP15+, CAM 5.2+, HMB45-

Sebaceous carcinomas: CK+, EMA+, CEA+, S100-, GCDFP-15 -, CAM 5.2+

Pilar Ca: CK+, EMA+/-, CEA-, S100-, GCDFP15-

Squamous Ca: CK+, EMA+/-, CEA-, S100-, GCDFP15-

Basal cell Ca: CK+, EMA-, CEA-, S100-, GCDFP15-

Melanoma: CK-, EMA-, CEA-, S100+, HMB45+, GCPFP15-

References:

Dr. Jayne Moffatt's handout, May 2003.
Cutaneous Adnexal Tumors..., Wick MR & Swanson PE, 1991, 238 pages.
Sampurna Roy, M. D. website
Cutaneous Adnexal Tumors..., Wick MR & Swanson PE, 1991, 238 pages (BWD's office)..
Expert Dermpath Consultant...John Maize.
Smith KJ, et. al., MAC & IHC, Am J Surg Pathol. 2001 Apr;25(4):464-71.

(posted 13 June 2003; latest addition 30 May 2007)