CLINICAL FEATURES

• 2nd most common stromal tumor of the esophagus, usually in the distal esophagus;

• 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. 544–546.

• 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