The patient went on to have resection of the mass.
The sections show respiratory mucosa extensively infiltrated by sheets of loosely cohesive and in places discohesive large cells with pleomorphic large nuclei, abundant mitoses, abundant apoptotic cells and focal areas of necrosis. Prominent vessels are seen within the lesion but no vessel invasion or perineural invasion is seen. The overlying respiratory epithelium is ulcerated in places but no atypia of the epithelium is seen.
The tumour cells are strongly positive for smooth muscle actin, desmin, myogenin and CD56 and negative for CD20, CD79a, CD3, S100, melan A, AE1/AE3, Chromogranin and synaptophysin.
FINAL DIAGNOSIS: Rhabdomyosarcoma (the lesion is favoured to be a solid variant of alveolar rhabdomyosarcoma).
features images from this case