Papillary Thyroid Carcinoma With an STRN::ALK Fusion Arising From a Mature Ovarian Teratoma.

Somatic malignancy arising from a mature ovarian teratoma is a rare phenomenon, occurring in 1% to 3.5% of cases. These somatic tumors are most commonly epidermal malignancies, but they can develop from any somatic component, including thyroid tissue. Increasing evidence suggests that in such cases, the pathogenesis is driven by the same mutational profile as seen in their conventional somatic counterparts. Here, we report the first case of an STRN::ALK fusion in a papillary thyroid carcinoma arising from the thyroid component of a mature ovarian teratoma. The patient presented with a 68 mm mass in the right ovary, which was histopathologically confirmed as a mature teratoma. Within the thyroid component, papillary thyroid carcinoma was identified. Next-generation sequencing revealed an STRN::ALK fusion, supported by positive ALK immunohistochemistry in the carcinoma. The identification of these genetic signatures not only aids in diagnosis but also provides potential therapeutic targets in the case of disease progression.