4.
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3.4.
Diagnosis: Granular cell tumor (GCT)
Histopathology: Figure 3: Low power view of granular cell tumor. Figure 4 High power view of ovoid granular cells displaying small nuclei and abundant eosinophilic cytoplasm with coarse granules.Figure 7: Imimmohistochemical S-100 protein stain showed strong positivity of the granular cells.
Discussion: Granular cell tumors are uncommon neoplasms that typically present as solitary, painless nodules of the dermis, subcutis, tongue, or other tissues/organs. Multiple GCTs are present in 4-25% of patients. GCTs more commonly occur during the fourth to sixth decades of life, but they can occur at any age. They are twice as common in women than in men. Black patients outnumber white patients by as much as 3 to 1, but other racial predilections have not
been established. Familial cases are rare. The tumor may occur at any body site. Approximately half of these lesions occur on the head and neck, and the tongue is the most frequently involved anatomic location. Other reported sites include the orbit, larynx, parotid gland, breast, esophagus, tracheobronchial tree, gastrointestinal tract, urinary bladder, male and female reproductive systems, and peripheral and cranial nerves. On gross examination, GCTs are grayish-white to yellow in color, well circumscribed, and firm in consistency.
Histologically, individual granular cells are ovoid-shaped with small nuclei and abundant eosinophilic cytoplasm containing numerous coarse granules. Immunohistochemically, most GCTs express vimentin, S-100 protein, neuron-specific enolase, and PGP (protein gene product) 9.5.
For decades, there has been much speculation regarding the origin of granular cell tumors. These benign tumors of uncertain malignant potential were called granular cell myoblastoma, since the tumor cells were found in muscle tissue. Subsequently a neural derivation was suggested and it is now commonly accepted that GCTs are derived from Schwann cells. Immunohistochemical studies substantiate a somewhat tenuous histogenetic connection of the myoblastoma with Schwann cells, as S-100 protein positivity has been demonstrated consistently in these and other non-neuronal tissue. Neuron-specific enolase has also been demonstrated, further substantiating a neuronal or neuroectodermal origin of the granular cell tumor.
Excisional therapy is recommended for GCTs, as 1-3% of all granular cell tumors have been reported to undergo malignant transformation. Benign GCTs rarely recur, and recurrence usually results from incomplete resection. The prognosis of malignant GCT is poor. A review of 34 patients reported death in 50% of patients at a median interval of 2.8 years. The most common sites of metastases are regional lymph nodes, lung, and bone. The size of the primary tumor and the presence of metastases are the most important prognostic indicators. The efficacy of radiation or chemotherapy has not been proven.
References:
I . Kyler JR, Krause SE, Mallory SB, Johnston YE. Multiple cutaneous granular cell tumors in childhood. Southern Medical Journal 81:1583 -6, 1988.
2. Ordonez NG and Mackay B. Granular cell tumor: a review of the pathology and histogenesis. Ultrastructural.Pathology 23:207-22, 1999.
3. Sahn EE, Dunlavey ES, Parsons JL. Multiple cutaneous granular cell tumors in a child with possible neurofibromatosis 34:327-30, 1996.
4. Tsuchida T, Okada K, Itoi E, Sato T, Sato K. Intramuscular malignant granular cell tumor. Skeletal Radiology 26:116-21, 1986.
5. White SW, Gallager RL, Rodman OG. Multiple granular-cell tumors. J Dermatol Surg Oncol 6:57-61, 1980.
6. Williams HK, Williams DM. Oral granular cell tumors: a histological and immunocytochemical study. J OralPathol Med8E"`8òp
My thanks to Drs. Helen Kim, Helen Thompson, and Susan Bayliss Mallory.
