Intrathymic Localization of Melanoma: A Brief Report of Two Cases and a Review of the Literature.

Intrathymic localizations of melanoma represent a very rare entity, with fewer than ten cases of intrathymic melanoma described in the literature. Herein, we describe two cases of patients who underwent surgical removal of a thymic mass at our thoracic surgery department between 2015 and 2022. The final pathological examination revealed a malignant melanoma in both cases; we therefore carried out a literature review to identify such rare and similar cases. In the first case, the intrathymic localization of melanoma was the first manifestation of the disease, posing a dilemma regarding the metastatic and primitive nature of the neoplasm. The second case described a thymic metastasis from a known previous cutaneous melanoma, for which the patient had successfully been treated six years earlier. After carefully reviewing the literature, we identified only six cases of verified primary intrathymic melanomas and one case of intrathymic metastasis resulting from melanoma previously described. Pathologists should be aware of the occurrence of this rare entity and mindful of the differential diagnoses. Several tools, including immunostaining of melanocytic markers and molecular investigations, are mandatory for final pathological diagnosis.