Results: A 13 year-old female with Hashimoto thyroiditis presented a 2.5 cm nodule in the left lobe of the thyroid. The total thyroidectomy specimen disclosed a firm, well circumscribed, non-encapsulated tumour. Microscopically, the tumour was composed by anastomosing clusters of squamoid cells in a sclerotic background without eosinophils. Intra-cytoplasmatic PAS/diastase positive material was focally found. The tumour cells expressed AE1.AE3, TTF-1 and p63 whereas no expression was observed for thyroglobulin, calcitonin and CD5. The Ki-67 labeling index was 5 %. In the molecular analysis no mutations were detected in BRAF or (K-, N-, H-) RAS genes nor RET/PTC or PAX8/PPARgamma rearrangements. The remaining thyroid showed Hashimoto-type thyroiditis. A cervical lymph node metastasis was identified. The patient was treated with radioactive iodine and is alive without signs of disease after 10 months of follow-up. Conclusion: SMECs may not disclose the classical eosinophilia and represent rare low-grade tumours that can give rise to metastases. The most frequent molecular alterations found in thyroid tumours were not detected in this case.