Features of atypical granular cell tumor on fine needle aspiration in an 8-month-old child: a case report

Granular cell tumors (GCT) are uncommon, generally benign soft tissue neoplasms that can affect virtually any site of the body, the most common locations being tongue, breast, upper respiratory tract, skin and soft tissues of upper extremities. Most patients are middle-aged, with a peak incidence in the fourth to sixth decade of life. GCT commonly presents as an asymptomatic slowly growing, painless nodule. Atypical and malignant counterparts are rare. Herein, we report on the case of an atypical GCT in an 8-months-old baby who presented at our Department with well-defined papulomatous lesion of one month duration on his back. A solitary, firm, painless nodule, about 1.5 cm in size was found on clinical examination. Fine needle aspiration cytology (FNAC) of the lesion was performed using a 22-gauge needle. Smears were stained with May-Grunwald-Giemsa and Papanicolaou stain. Cytomorphology revealed highly cellular tumor composed of loosely dispersed group of cells and stripped bare nuclei. The cells were large, polygonal to spindle-shaped with an abundant eosinophilic granular and fragile cytoplasm and round to oval nucleus with fine chromatin pattern. Focally cells were larger with prominent nucleoli. Rare mitotic figures were present. Diagnosis of malignant mesenchymal tumor was suggested and excision was advised. Histological examination revealed tumor tissue composed of large, polygonal cells with granular eosinophilic cytoplasm, vesicular nuclei, moderate nuclear pleomorphism and focally prominent nucleoli. There were 2 mitosis per 10 HPF. The tumor cells were positive for S-100 and vimentin. A diagnosis of atypical GCT was established. In conclusion, benign GCT has a distinctive cytomorphologic appearance and can be diagnosed on the basis of the cytological examination alone. Nuclear pleomorphism, spindling of the cells, prominent nucleoli and mitotic figures are worrisome features that suggest malignancy and necessity of histological examination. Considering the patient's age and atypical morphology, to the best of our knowledge, there have been up to 15 GCT cases described in medical literature by now in the children less than one year.