Spindle cell tumour with thymus‐like differentiation (SETTLE) on fine needle aspiration cytology: A case report highlighting diagnostic pitfalls

Abstract

A 7‐year‐old girl presented with a painless neck swelling localised near the left lobe of the thyroid gland, which was initially investigated by fine needle aspiration cytology. This raised a differential diagnosis of medullary thyroid carcinoma and small round blue cell tumour. Only after several additional clinical investigations and a total thyroidectomy was a definitive diagnosis of spindle cell tumour with thymus‐like differentiation (SETTLE) reached. This case report highlights how contemporaneous clinical and investigation findings made arriving at a definitive diagnosis challenging, contributed to diagnostic delay, and ultimately influenced choice of treatment.

Cytomorphology of monomorphic spindle epithelial tumor with thymus‐like elements: A case with local recurrence after subtotal resection

“…Moreover, molecular rearrangement testing for SS18/SSX by FISH yielded negative results in all cases tested. For a detailed overview, please refer to Table 1 5,7,9,11‐18 …”

“…For a detailed overview, please refer to Table 1. 5,7,9,[11][12][13][14][15][16][17][18] Lastly, in the report of the prior resection (hemithyroidectomy), the tumor involved the surgical margins and had focal areas that were suspicious for lymphatic invasion. No lymph nodes were identified and post-operative imaging showed no evidence of metastatic disease and normal thyroid function tests.…”