• appendix fecalith:
  1. calcified: variably calcified lumenal fecal ball
  2. non-calcified: obvious, inspissated lumenal fecal ball
• appendicitis:
  1. appendicular mucositis (pinpoint to diffuse)
  2. ASA (acute suppurative appendicitis, typical histology)
  3. ASA, gangrenous appendicitis
  4. ASA, abscessed appendicitis
  5. perforated or ruptured appendicitis
  6. subacute appendicitis: not enlarged & eosinophils quite a part of the inflammatory rcn.
  7. subacute hypertrophic (enlarged) appendicitis: eosinophils and other inflammatory cells and fibrosis. If does not have any evidence in history c/w appendicitis, it might be "eosinophilic appendicitis" in the manner of other eosinophilic processes in other GI locations. Or might refer to as "eosinophilic appendicopathy" [LCH-86-3506].
  8. chronic resolving appendicitis (not an enlarged appendix)
  9. chronic idiopathic granulomatous appendicitis (enlarged & no evidence of Crohn's)
  10. chronic granulomatous appendicitis (enlarged & evidence of Crohn's)
  11. chronic non-specific hypertrophic appendicitis
  12. periappendicitis
• other:
1. Neurogenic appendicopathy: nerve proliferation and an increased number of endocrine cells are typical for NA. This study characterizes the epidemiology, histology, clinical appearance and therapy of NA; they evaluated the incidence of NA in macroscopically normal specimens from patients presenting the symptoms of acute appendicitis and in incidental appendectomies.
• tumors:
  1. carcinoid:
     • ordinary, conventional: a small percentage of even these classical ones may be devoid of neurosecretory granules³.
     • those more aggressive¹: mucinous carcinoid [LMC-98-6306](adenocarcinoid; goblet cell carcinoid; crypt cell carcinoma; mixed adenocarcinoma-carcinoid [LMC-04-3502]): replicates mucinous cells of crypts: no epithelial dysplasia; mixture of goblet or signet ring cells, neuroendocrine cells (rarely more than 30% component), and Paneth cells. These types are said to have 80% or less five year survival. Must have been completely excised. May need right hemicolectomy². If young (maybe less than 50-60) or show things like perinueral (neurotropism) or lympovascular invasion, may also need adjuvant chemo².
     • controversy: call it "atypical carcinoid" or "malignant carcinoid" versus "carcinoma (well or moderately differentiated) with carcinoid features"³?
     1. growth pattern: to be in the carcinoid realm, must have one of the carcinoid growth patterns (insular, acinar [rosette-like, tubular, and trabecular [ribbons])³.
     2. small cell neuroendocrine carcinoma if poorly differentiated³.
     3. carcinoids tend to be ck7 & ck20 negative.
     4. carcinoma with neuroendocrine markers but negative for carcinoid histological pattern = "carcinoma with neuroendocrine features".
     5. AFIP carcinoids include malignant according to histology plus size & location:
  2. hyperplasia (mucosal) to mucocoel: examples [LMC-85-3923; LMC-86-2319]; can get so tensely dilated that begin to mucous dissect the thin wall, get inflamed & burst or incipiently burst [L07-2017], resulting in an appendico-peritoneal fistula producing simple mucus ascities, to mucus ascites with obviously proliferated low grade neoplastic epithelium within the ascitic mucus [L07-3631]..."low grade appendiceal mucinous neoplasm", some 50% of which succumb to the disease within 10 years⁴. Pseudomyxoma peritonei is mucus ascites with actual low (or higher) grade invasive mucinous carcinomatous serosal implants...whether of ovarian, appendicular or other primary origin.
  3. adenocarcinoma

References:

1. Weidner N, The Difficult Diagnosis in Surgical Pathology, 1996.(EBS's office)
2. Lex. Med. Center Oncology Conference.
3. Principles & Practice of Surg. Path. and Cytology, [3 vol. text] Silverberg, SC, 3rd Ed. 1997.
4. Am. J. Surg. Path. 27:1089-1103, 2003.
5. Young RH, "Pseudomyxoma peritonei and selected other aspects of the spread of appendiceal neoplasms", Semin. Diagn. Pathol. 21(2):134-50, May 2004.
6. Franke C, et. al., "Neurogenic Appendicopathy in Children", Eur. Pediatr. Surg. 12(1):28-31, Feb. 2002.

(posted about 2003; latest addition 8 May 2007)