Thiamazole, also known as Methimazole, is a drug used to eliminate the thyroid gland and is prescribed for patients with hyperthyroidism. A rare side effect of this is bone marrow suppression, where neutropenia can lead to life-threatening opportunistic infections. An even rarer side effect is benign (relative) plasmacytosis.

This patient, treated with thiamazole, had both neutropenia and plasmacytosis. The total leukocyte count was . The chart also showed a substantial number of thrombocytes, consistent with acute infection.