Case for diagnosis. Granular cell tumor.

Granular cell tumor is a rare benign neoplasm of neural origin. We report the case of a female patient, 27 years old presenting a brown-red nodule in the right arm, which pathological examination showed to be formed by polygonal cells with eosinophilic granular cytoplasm and immunohistochemistry positive for S100 protein and CD68. Granular cell tumor is usually solitary and in half the cases located in the head and neck areas, 30% of these in the tongue. It is most frequent between the third and fifth decades of life in women and people of African-American ethnicity. Its origination is controversial, including the possible origins in muscle, fibroblasts, neural crest, neural sheath or histiocytes. The positivity for S-100 and CD68 suggest the neural origin.

CASE REPORT

Twenty-seven year old female patient, phototype V, presented a lesion in the right arm for one and a half years, without associated symptoms. Dermatological examination revealed a smooth-surfaced, brownish, painless nodule, movable within deep layers, measuring three centimeters and located in the right arm (Figure 1). Pathological examination of the surgical specimen showed dense proliferation of large cells with granular-appearing eosinophilic cytoplasm, distinct membranes, central or eccentric nuclei and slightly conspicuous nucleoli. The neoplastic cells formed syncytia in some areas and were inserted within the interstices of a desmoplastic stroma, with scarce focal lymphocytic infiltration. The results of immunohistochemical examination were positive for S100 protein, CD63 and CD68 (Figure 2).

FIGURE 1

Smooth-surfaced hyperchromic nodule, movable in the deep layers, located on the right cubital fossa

FIGURE 2

Hematoxilineeosin stained fragment, histopathological exam showing dense proliferation of cells with a wide eosinophilic cytoplasm, central nuclei, and slightly conspicuous nucleoli. Immunohistoc hemistry positive for protein S100 e CD68

DISCUSSION

Granular cell tumor (GCT), also known as Abrikossoff tumor, is a relatively rare benign condition that originates in Schwann cells and presents clinically as a slow-growing, painless, solitary nodule, that in half the cases is located in the head and neck areas, including 23% of these in the tongue.[1,2] GCT can affect patients of all ages, races and genders, but is more frequent between the third and fifth decades of life in women and people of African-American ethnicity.[2] This tumor was first described in 1926 by Abrikossoff; however, its pathogenesis has been the object of research and debate for many years. In 1935, Feyrter suggested a neural differentiation. In the 1960s, clinical and pathologic origins from Schwann cells were reported.[1,2] Clinically, it appears as an asymptomatic dermal or subcutaneous nodule, skincoloured or brown-red, ranging from 0.5 to 3 centimeters in diameter, with slow growth and generally benign behavior.[3-5] Some patients may have warty, itchy or painful lesions.[3] Half of these tumors develop in the head and neck regions, with the tongue as the most common site.[1-3] However, any organ or tissue can be affected, such as the digestive and respiratory tracts, pituitary and parotid glands, skeletal muscles and eyes.[3,5] Multiple lesions occur in 5-25% of cases and reports in children are rare.[3] Histologically, the dermis shows polygonal cells with abundant granular eosinophilic cytoplasm, central or eccentric vesicular nucleus containing diastase resistant, and PAS positive granules. Cellular boundaries are usually inaccurate, resembling a syncytium.[4] Under electron microscope, degenerated myelinated axons are seen in the cytoplasm of these tumor cells.[3] Positive expression of S-100, CD 68, CD57, neuron-specific enolase and vimentin confirms the neural origin, although the classic form of this tumor does not carry any resemblance to other tumors of the peripheral nerve sheath.[3,4,6,7] Epidermis may present pseudoepitheliomatous hyperplasia.[7] Malignant cases represent 12% and usually have a poor prognosis. Differential diagnoses include melanocytic nevus, dermatofibromas and adnexal tumors. Treatment involves complete excision, because if incompletely removed the local recurrence rate is high.[4,5]