We Won the Battle but did we win the War? A Rare Case of Perianal Langerhans Cell Histiocytosis Complicated by Myelodysplastic Syndrome

Langerhans cell histiocytosis is a rare group of proliferative histiocytic disorders of the bone-marrow derived langerhans cell. Largely a pediatric disease, it has a wide clinical spectrum ranging from a single lesion commonly found in skin and bones to multisystemic organ involvement. Adult-onset Langerhans cell histiocytosis as a perianal lesion is an uncommon presentation reported in a few case reports. The concurrence of Langerhans cell histiocytosis and myelodysplastic syndrome has been reported in four other adult cases in the English literature. Here we report a rare case of an 81 year old male with thrombocytopenia and a recurrent perianal lesion diagnosed as Langerhans cell histiocytosis with myelodysplastic syndrome. We highlight the importance of considering Langerhans cell histiocytosis in the differential when working up perianal lesions. We also review the literature to determine an underlying mechanism of association between langerhans cell histiocytosis and myelodysplastic syndrome and other hematologic malignancies and the need to monitor for these hematologic disorders in patients with Langerhans cell histiocytosis.