LMP1-Positive Composite Tumour of Larynx: A Diagnostic Quandary

Malignant spindle cell tumours of the larynx are rare, of which the most common are Spindle Cell Squamous Carcinomas (SCSCs). Sarcomas are extremely infrequent in the larynx. Composite tumours, further, are quite unheard of, except for rare case reports. This case report describes a spindle cell malignancy of the larynx in an elderly male, which posed a diagnostic difficulty due to its unique morphological and immunohistochemical features. The tumour was superficial, polypoidal with the proliferation of malignant spindle cells and abundant mitoses under an ulcerated epithelium. Occasional squamous cell rests with keratin pearls were present. Spindle cells were strongly immunoreactive for vimentin, smooth muscle actin and squamoid cells were p63 positive. Desmin was negative. The dilemma in diagnosis was of a SCSC with smooth muscle differentiation against a composite tumour. The tumour also turned out to be positive for Epstein Barr Virus Latent Membrane Protein-1 (EBV-LMP1), establishing a noteworthy association.