Leiomyosarcoma of the larynx: critical analysis of the diagnostic role played by immunohistochemistry.

Laryngeal leiomyosarcoma (LMS) is definitely considered a rare occurrence: our exhaustive literature review disclosed to date only 45 cases (including the new case we have reported). The morphological diagnosis of laryngeal LMS may be problematic on conventional light microscopy especially in small laryngeal specimens. In the past, LMSs of the larynx were frequently confused with other spindle-cell malignant tumors. Nowadays, immunohistochemical investigations are considered necessary to distinguishing LMS from other spindle-cell tumors. On immunostaining, LMS is usually positive for muscle-specific actin and negative for cytokeratins and epithelial membrane antigen. In most cases, immunohistochemical study allows reliable diagnosis of LMS, but it can produce ambiguous or inconclusive results when the tumor cells lack specific immunohistochemical reactivity. In these controversial cases, LMS diagnosis has to be substantiated by electron microscopy. Distinguishing laryngeal LMS from other spindle-cell malignancies plays a role not only in academic interest. Confusion in the diagnosis of a spindle-cell laryngeal malignancy could result in inappropriate clinical management and inadequate treatment.