Pseudosarcoma of the larynx: the value of ploidy analysis.

An 82-year-old male presented with a two-month history of hoarseness. A 2 cm pedunculated lesion was removed from the base of his epiglottis. Microscopy showed a polypoid atypical spindle cell lesion. Multiple levels failed to reveal an invasive squamous cell carcinoma. On the basis of haematoxylin and eosin stained sections the main differential diagnosis was a pseudosarcoma with an overlying dysplastic squamous mucosa or infiltrating spindle cell carcinoma. Immunohistochemistry showed positive staining for vimentin but no convincing staining with antibodies to cytokeratin and EMA. Ultrastructural analysis also failed to reveal epithelial characteristics. Ploidy analysis by static cytophotometry of the spindle cell proliferation revealed an aneuploid stem line with a DNA index of 1.67. On the basis of this the process was felt unlikely to be reactive and a diagnosis of a spindle cell squamous carcinoma was made. This diagnosis was subsequently supported by a clinical recurrence of the nodule at a six-month follow-up.