NK/T-cell Lymphoma, Nasal type
The most common site of involvement in NK/T-cell lymphoma is the nasal cavity. In nasal lesions, the overlying respiratory mucosa is frequently infiltrated and shows squamous metaplasia (as seen here) or even pseudoepitheliomatous hyperplasia (see higher magnification in slide 4) which can mimic squamous cell carcinoma. The tumor is composed of small, medium-sized, or large cells which are admixed with apoptotic bodies and inflammatory cells. There is angiocentric and angioinvasive growth leading to ischemic necrosis and ulceration of the involved tissues.