Answer: Acute leukemia

Histology: The biopsy shows some residual nasal mucosa but is composed predominantly of necrotic tissue with associated inflammatory cells. Fungal stains in this case were negative. The mononuclear component consists of predominantly mononuclear cells. Many of these cells are small and pyknotic. There is a rare polymorphonuclear leukocyte. The majority of the cells are immature hematopoietic cells with a high nuclear to cytoplasmic ratio reminiscent of blasts. Much of the necrotic tissue also has ghosts of immature cells within it suggesting necrotic tumor. Immunoperoxidase stains demonstrated that the immature cells stain for C-KIT and CD-34 and were focally positive for myeloperoxidase. These findings would be consistent with involvement by acute myelogenous leukemia.

Discussion: Necrotic sinusoidal tissue often is a sign of fungal sinusitis and such cases should be stained for fungus. The stains in this case, however, were negative. This type of necrosis also can be seen in Wegener’s granulomatosis. However, in this case there is no evidence of vasculitis or giant cells which can be associated with this condition. Chronic bacterial sinusitis is not usually associated with abundant necrosis and when necrosis is observed it should suggest the possibility of fungal sinusitis. In this particular case, the patient was known to have acute leukemia and the presence of large collections of immature cells (blasts) alerts the pathologist that this is not routine acute inflammation. The patient was thought to have fungal sinusitis due to immunosuppression from the leukemia and therapy. The presence of the large immature cells suggests involvement by acute leukemia. Immunoperoxidase stains are helpful in confirming the presence of blasts. These immature cells stain with C-KIT and CD-34 which is typical of acute non-lymphocytic leukemia.