Black hairy tongue (BHT) developed in five patients (2.6%) among 192 patients undergoing chemotherapy for malignant brain tumors. Three patients with a history of diabetes mellitus developed BHT within 10 days after the initiation of chemotherapy. The other two patients suffered more than 100 days after induction and lymphopenia of grade 3 or worse developed for more than 20 days, which was not observed in the three patients with diabetes. We found that BHT could develop after chemotherapy for malignant brain tumors. Patients with diabetes mellitus presented early after chemotherapy, while patients with longstanding severe lymphopenia presented in late phase.
Keywords: Black hairy tongue; Chemotherapy; Glioblastoma; Primary central nervous system lymphoma.