Follicular mucinosis occurring after bone marrow transplantation in a patient with acute lymphoblastic leukemia

Follicular mucinosis (FM) is characterized histologically by mucinous degeneration of the outer root sheath of the hair follicle and sebaceous gland, accompanied by inflammatory infiltrate. It can occur as a primary idiopathic disorder or in association with benign or malignant diseases, most notably mycosis fungoides. In addition, it also can be found incidentally on histology. We describe an unusual case of follicular mucinosis in a 19-year-old man with acute lymphoblastic leukemia (ALL). One month after bone marrow transplantation, he developed cutaneous graft-versus-host disease (GVHD) involving the palms and soles, which was followed 12 days later by the appearance of multiple erythematous follicular papules and plaques on his face, auricles, and postauricular area. Biopsy of follicular plaque revealed changes of follicular mucinosis without evidence of graft-versus-host disease or leukemia cutis. The follicular rash was associated with prominent peripheral eosinophilia. The rash and eosinophilia resolved after 2 and 4 weeks, respectively. In conclusion, we report a case of FM occurring as a transient reaction during the course of cutaneous GVHD following bone marrow transplantation for ALL. Awareness of this condition may avoid undue concern that the rash might represent a manifestation of GVHD, cutaneous relapse of the hematological malignancy, or a drug allergy.