Spindle cell variant of papillary thyroid carcinoma: A diagnostic challenge - A rare case report with brief review of literature.

Objective: Primary Spindle cell tumors of the thyroid are very rare and comprise a myriad of differential diagnoses ranging from reactive proliferations to neoplastic processes. Differentiation amongst these rare entities is of utmost importance as it defines the prognosis and also guides future therapy.

Case Report: Hereby, we present a rare case of spindle cell variant of papillary thyroid carcinoma in a sixty-four-year-old female which posed a diagnostic challenge on histology. Microscopy showed a well-circumscribed spindle cell lesion with areas of infiltration and entrapment of colloid-filled thyroid follicles. There were no characteristic features of papillary carcinoma. A panel of immunohistochemistry markers was advised which clinched the diagnosis as the spindle tumor cells were positive for thyroid papillary carcinoma markers. Although papillary carcinoma usually has an indolent course, however interestingly this patient presented with lymph node metastasis one month after surgery which cytologically showed features of malignant spindle cell neoplasm.

Conclusion: Through this case report we wish to highlight the cytological, histopathological as well as immunohistochemical features of this rare variant of papillary carcinoma.