Diffuse Normolipemic Plane Xanthoma Associated With Monoclonal Gammopathy.

Diffuse normolipidemic plane xanthoma is a rare acquired dermatosis of the non-Langerhans histiocytosis subtype, often associated with underlying hematologic disorders, with half of the reported cases linked to lymphoproliferative disorders. This case report describes a 52-year-old woman presenting with asymptomatic, yellowish plaques symmetrically distributed on the eyelids, cervical region, axillae, upper back, and upper thighs, which had evolved over a two-year period (images of the eyelids and upper back are not provided). Skin biopsy was consistent with the diagnosis of plane xanthoma. Laboratory evaluation showed normal lipid levels, but elevated serum IgG and the presence of a monoclonal band, leading to the diagnosis of monoclonal gammopathy of undetermined significance (MGUS) after further workup. Over 18 months after diagnosis, the patient remains under follow-up in both the dermatology and hematology departments, with no signs of disease progression.