Mucinous metaplasia of the squamous epithelium of the glans penis is very rarely seen in the setting of Zoon’s balanitis. We report a case of 40 year old male with a past medical history of paroxysmal nocturnal hemoglobinuria, status-post allogeneic hematopoietic cell transplantation from an HLA-matched sibling 6 years prior to evaluation, complicated by oral and cutaneous chronic graft-versus-host disease. Mucinous metaplasia was confirmed by PAS and Mucin stains, and plasmacytosis was confirmed by immunohistochemistry for CD138 and MUM1 markers. Kappa and Lambda immunostains revealed a polyclonal pattern. The etiology of zoon’s balanitis as well as the significance of mucinous metaplasia in these setting are unclear and need to be further investigated.
 Val-Bernal, J.F. and Hernández-Nieto, E. (2000) Benign mucinousmetaplasia of the penis. A lesion resembling extramammary Paget’s disease. Journal of Cutaneous Pathology, 27, 76-79. doi:10.1034/j.1600-0560.2000.027002076.x
 Wollina, U. (2010) Ablative erbium: YAG laser treatment of idiopathic chronic inflammatory non-cicatricial-balanoposthitis (Zoon’s disease)—A series of 20 patients with long-term outcome. Journal of Cosmetic and Laser Therapy, 12, 120-123. doi:10.3109/14764171003706125
 Marconi, B., Campanati, A., Simonetti, O., Savelli, A., Conocchiari, L., Santinelli, A., Pisa, E. And Offidani, A. (2010) Zoon’sbalanitis treated with imiquimod 5% cream. European Journal of Dermatology, 20, 134-135.