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Case 67- Discussion

Uploaded: 2007-11-28, Updated: 2010-08-07

 

Granular Cell Tumor

The Key Features

  • Fine granular eosinophilic or amphophilic cytoplasm

  • Pseudoepitheliomatous hyperplasia of overlying epidermis

  • S100+, PAS/D +

  • Cytoplasmic secondary lysosomes under EM

CLINICAL FEATURES

 
  • M>F, average age 40-50 years;

  • Excellent prognosis.

GROSS FINDINGS

 
  • Usually small pale white/yellow, non-encapsulated, and variably (well to poorly) circumscribed nodules;

  • Cut surfaces: solid, fleshy, characteristically pale yellow-tan or gray-yellow; free of liquefaction, necrosis or bleeding;

  • The overlying skin or mucosa is thickened and may have a cobblestone appearance.

MICROSCOPIC FINDINGS

 
  • Tumor cells arranged in nests or clusters separated by collagenous fibrous;

  • Granular cells: polyherdral, round, spindle, or epithelioid cells; nuclei, from small/dark to large/vesicular chromatin;

  • Abundant eosinophilic or amphophilic (not bright red as seen in oncocytes) granular cytoplasm, mostly small and regular, occasionally larger round homogenous eosinophilic droplets;

  • Pseudoepitheliomatous hyperplasia of overlying squamous epithelium, may mimic SCC;

  • Close association between granular cells and peripheral nerve;

  • Malignant features: atypical mitosis, necrosis, pleomorphism and ulceration of overlying epithelium. However, mild to moderate atypia do not indicate malignancy.

DIFFERENTIAL DIAGNOSES

 
  • Leiomyoma: bright pink cytoplasm, no granular pattern;

  • Rhabdomyoma: contains cross-striation and glycogen;

  • GIST: no granular cytoplasm, CD117+;

  • SCC: marked acanthosis of overlying epithelium of granular cell tumor may mimic SCC.

IMMUNOHISTOCHEMISTRY AND SPECIAL STAINS

 
  • S100+, neuron-specific enolase, CD68+, calretinin+, CD56+, CD57+;

  • Negative for CD117, epithelial, muscle, endothelial, and glial cell markers;

  • The granules are phagolysosomes and stain positive with periodic acid-Schiff (PAS).

ELECTRON MICROSCOPIC FINDINGS

 

Archives of Pathology and Laboratory Medicine: Vol. 125, No. 4, pp. 544546.

 
  • Highly characteristic pleomorphic secondary lysosomes within the cytoplasm, and they are membrane-bound autophagic vacuoles that contain cellular debris. These secondary lysosomes contain dense granular materials and whorls of membranes

TREATMENT AND PROGNOSIS

 
  • Excellent prognosis

REFERENCES

 
  • AFIP Atlas of Tumor Pathology - Fourth Series. Nonmelanocytic Tumors of the skin;

  • Rosai and Ackerman's Surgical Pathology. 9th Edition;

  • Enzinger and Weiss's Soft Tissue Tumors, 4th Edition. By Drs. Sharon Weiss and John Goldblum.

  • http://www.emedicine.com/med/topic2493.htm