Psammomatous melanotic schwannoma localized in the mediastinum: diagnosis by fine-needle aspiration cytology.

The cytological characteristics are presented in a case of psammomatous melanotic schwannoma localized in the mediastinum, diagnosed by fine-needle aspiration cytology (FNAC), with later histological confirmation. This lesion affected a 38-year-old male, with a tumor measuring 5 cm in diameter located in the posterior mediastinum in contact with the spinal cord, with erosion of the adjacent vertebra (T5), that caused constant pain localized in the right scapular region with an evolution of several weeks. The cytological characteristics of psammomatous melanotic schwannoma are discussed, along with the histological and immunohistochemical features of this infrequent neural tumor, which aid in establishing a differential diagnosis. The importance of a correct histological diagnosis of this tumor is of particular clinical relevance after having been identified as one of the possible components of Carney's complex. This possibility demands a meticulous patient exploration in search of any other components that make up this complex, given the aggressive character of some of them. These lesions could, if not detected early enough, produce fatal consequences for the patient, fundamentally in those patients with cardiac myxomas. In this case, following an exhaustive clinical examination there was no pathology associated with this complex. It is therefore considered to be an isolated psammomatous melanotic schwannoma, and not a part of Carney's complex.