Primary malignant melanoma with pseudovascular morphology: a diagnostic pitfall.

Melanoma is a neoplasm with a heterogeneous clinical presentation and several histopathological variants have been described. Although histopathological evaluation remains the diagnostic gold standard, unusual morphology of some melanomas can lead to pathologic misinterpretation, as they can be confused with other non-melanocytic tumors. Here, we present a case of nodular melanoma with pseudovascular morphology characterized by uncommon empty branching slit-like spaces, reminiscent of rete testis vessels, for which we suggest the name of retiform melanoma to distinguish it from angiomatoid melanoma. Immunohistochemical analysis and ancillary molecular tests helped us characterizing this neoplasm, underscoring the need for clinical-morphological-molecular correlation for the correct diagnosis of unusual cases.