Granular cell tumor of hand presenting as subcutaneous nodule mimicking dermal adnexal tumor: A diagnosis by cytology
A 21-year-old female presented with a slow growing, dome-shaped, painless nodule on left index finger for 15 months. She had no history of pain or fever. She had a history of thorn injury at this site before 2 years. Clinically, a single, soft-to-firm, slightly mobile, nontender swelling was noted without significant changes of the surface of the skin. Swelling measured 2.0 × 2.3 cm in size []. No other masses were found. Clinical diagnosis of the primary dermal adnexal tumor was considered and FNAC was requested. Plain radiographs showed no bony lesion. Laboratory evaluations were unremarkable.\nThe tumor was sampled by a 22 G needle. The smears were prepared, fixed immediately in 95% ethanol and air dried. Smears were stained with Hematoxylin-eosin (H and E) and May-Grunwald-Giemsa (MGG) stain. Smears were highly cellular, composed of syncytial clusters and many scattered single tumor cells. The cells were fairly uniform, round to polygonal with abundant, finely granular cytoplasm, eccentric round to slightly oval nuclei, evenly distributed chromatin, and occasional small nucleoli. Cytoplasmic borders were poorly defined. The cells were fragile, with many stripped nuclei in a background of finely granular material. Nuclear atypia, mitosis, and necrosis were not observed []. A cytologic diagnosis of benign GCT was made and excision was advised.\nAt surgery, the tumor was located in the dermis and subcutaneous area without continuity with any structures. The tumor was completely excised with wide margins. The tumor was ill-defined, firm with a homogenous gray white cut surface. The tumor measured 1.9 × 2.0 cm in size. Histopathological examination revealed sheets of tumor cells. Tumor cells were large, round to polygonal with ill-defined borders. The cells had abundant granular eosinophilic cytoplasm, round to oval centrally or eccentrically located nuclei with mild variation in size, and occasional small nucleoli. Few larger, brightly eosinophilic ovoid bodies surrounded by a clear halo were identified. Mitoses and necrosis were not evident. On immunohistochemistry, the tumor cells show strong cytoplasmic reaction for the S-100 protein. Tumor cells were also positive for neuron-specific enolase and vimentin. CD68 was negative in tumor cells []. The cells were negative for cytokeratin, desmin, alpha smooth muscle actin, and HMB-45. The diagnosis of benign GCT was confirmed. Postoperatively the hand incision healed uneventfully, and the patient is well after 15 months without recurrence.