Anus and perianal area
Benign or nonneoplastic lesions
Granular cell tumor

Author: Elliot Weisenberg, M.D. (see Authors page)

Revised: 3 October 2017, last major update May 2014

Copyright: (c) 2002-2017, PathologyOutlines.com, Inc.

PubMed Search: Anus granular cell tumor

Cite this page: Weisenberg, E. Granular cell tumor. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/anusGCT.html. Accessed December 11th, 2017.
Definition / general
Terminology
  • Synonyms and obsolete terms include granular cell schwannoma, granular cell nerve sheath tumor, granular cell myoblastoma, Abrikossoff tumor
Epidemiology
Sites
  • In anal mucosa or perianal skin
  • May be found near peripheral nerves
Clinical features
  • May present as asymptomatic nodule or polyp or may mimic hemorrhoids causing pain, bleeding, discomfort
Prognostic factors
  • Vast majority of granular cell tumors are benign
  • Characteristics from various references state that lesions greater than 5 cm in diameter, with increased cellularity, tumor cell necrosis, > 2 mitoses per 10 HPFs, spindled tumor cells, deep location, nuclear pleomorphism and prominent nucleoli are at higher risk of showing malignant behavior; but no findings are pathognomonic of malignancy except vascular invasion or metastasis
  • There are clearly documented examples of malignant behavior from typical, small, bland granular cell tumors
  • Incompletely excised tumors may recur
Case reports
Treatment
  • Conservative local excision
Clinical images

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Anal polypoid mass

Solitary cutaneous nodule

Gross description
  • Usually firm, poorly circumscribed, pale tan yellow nodule
  • Overlying skin may appear thickened
Microscopic (histologic) description
  • Identical to granular cell tumors elsewhere
  • Sheets, nests, cords or trabeculae of tumor cells
  • Most cells are large, oval to round, with prominent granular cytoplasm
  • PAS positive, diastase resistant granules are present in from 1/3 (Fletcher: Pathology and Genetics of Tumours of Soft Tissue and Bone, 3rd edition, 2006) to nearly all cases (Fletcher: WHO Classification of Tumours of Soft Tissue and Bone, 4th edition, 2013)
  • Nuclei vary from small, round, and hyperchromatic to those with larger size, more open chromatin and visible nucleoli
  • Smaller cells with coarse granules known as interstitial cells or angulate body cells are also present
  • Perineural invasion may be seen but is not indicative of malignancy
  • A desmoplastic stromal reactive may be seen in older lesions
  • The overlying skin may show prominent pseudoepitheliomatous hyperplasia that may mimic squamous cell carcinoma
Microscopic (histologic) images

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Voluminous cells

Malignant tumor

S100+

NSE+

Positive stains
Negative stains
Electron microscopy description
  • Rarely employed for diagnosis
  • Phagolysosomes with prominent myelin figures
  • Interstitial cells contain parallel microtubules, lipids and cytoplasmic processes
Differential diagnosis