Langerhans cell histiocytosis associated with myelodysplastic syndrome in adults.

Background: Myelodysplastic syndrome (MDS) is a group of bone marrow disorders associated with dyplasia of myeloid elements that may have cutaneous manifestations including infections, vasculitis, Sweet's syndrome, pyoderma gangrenosum, erythema elevatum diutinum, and leukemia cutis. These cutaneous manifestations are attributed to the underlying bone marrow defect. Langerhans cell histiocytosis (LCH) is primarily a pediatric disease, and rarely LCH has been described in association with pediatric MDS. We are aware of only a single case report of LCH associated with MDS in an adult.

Methods: We report two new cases of LCH in elderly patients with underlying MDS. The specimens were examined by routine microscopy as well as immunohistochemical stains for S100 protein and CD1a.

Results: Both patients were elderly men with established diagnoses of MDS. One presented with a solitary pruritic papule while the other had a 2-year history of erythematous papules involving the trunk and extremities. Histologic examination revealed intraepidermal and dermal collections of mononuclear cells with reniform nuclei. The cells were strongly positive for S100 and CD1a, confirming their identity as Langerhans cells.

Conclusion: Cutaneous LCH may be associated with underlying MDS in adults and should be considered in the differential diagnosis of cutaneous eruptions in patients with MDS.