Granular cell tumors are unusual, rare neoplasm; they most commonly involve the head and neck region in 30-50% of cases
1, especially the tongue. Involvement of the genitourinary system is rare with only 12 cases of granular cell tumor of the urinary bladder were reported.
Granular cell tumor was initially described by Abrikosoff in 19262. It is believed to be a benign tumor that arises from neural cells3,4 probably the Schwann cell. Malignant GCT comprise fewer than 2 % of all GCT5. Only two cases of malignant granular cell tumors were reported in the literature6,7. In few cases of granular cell tumors, Schwann cells in the pathology were not present (80.
Granular cell tumors (GCT) are typically solitary and smaller than 3 cm. Up to 10% of GCT are multiple9,10. GCT are particularly multiple in black patients11,12.
Granular cell tumors are usually benign but are commonly confused for malignant tumors since these lesions may present as solid tumors with ill defined margins and ulcerating surface and their size vary up to 12 cm, and hence could be confused with transitional, squamous cell carcinoma or sarcoma in the urinary bladder. Although most patients affected are middle-aged, it can affect persons of varying ages with a peak incidence in the fourth through the sixth decades of life. A slight female predominance exists with an estimated female to male ratio of approximately 3:2.
The malignant lesions are usually larger (4-15cm) and may be locally destructive, causing symptoms depending on the site (Pressure, obstruction, hemorrhage, ulceration, secondary infection). The malignant GCT has two distinct variants. The first variant has a benign histopathology indistinguishable from those found in benign tumors13. The second consists of lesions that are more readily identifiable as malignant. Necrosis, nuclear pleomorphism, spindling and increased mitotic activity are the features of malignancy13,14.
The symptoms of GCT depend on the location and the size of these tumors. Gross hematuria is the most common symptom in patients with GCT of the urinary bladder but the patient may be asymptomatic and GCT could be found incidentally.
The tumor cells are large polygonal, oval or bipolar cells with abundant, fine or coarsely granular eosinophilic cytoplasm with well defined cell borders and small, pale-staining or vesicular nucleus eccentrically located in the cell. They can be arranged in nests or sheets. Granular cells demonstrating nuclear enlargement, hyperchromatism and pleomorphism, or with mitotic activity, are suggestive of malignant variant of this tumor. The confirmatory immunohistochemical stain pattern consists of positive staining for S100 protein, neuron specific enolase, laminin, CD 68 and various myelin protein15 and negative staining with epithelial (cytokerarins), sarcoma (vimentin, desmin, alpha smooth muscle actin) markers. The non reactivity to epithelial and muscle markers differentiates GCT from carcinomas and sarcomas16.
Granular cell tumors (GCT) mostly follow a clinically benign course. Conservative surgical treatment with transurethral resection of the tumor or partial cystectomy appears to be the treatment of choice. Malignant GCT is extremely rare and the treatment include radical cystectomy.
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