Endocrine Abstracts

Introduction: Xanthoma disseminatum (XD) is a rare, non - familial disease characterised by lipid deposition in skin and internal organs due to histiocytic cell proliferation, classified as a non-Langerhans cell histiocytosis. The disease is characterised by symmetrically distributed, coalescing cutaneous papules, initially red–brown then yellow involving the face, trunk, flexural and intertriginous areas. Involvement of mucous membranes has been reported. The upper and lower respiratory tract may also be affected, along with the gastrointestinal tract and bone. In addition, involvement of the pituitary gland, with diabetes insipidus (DI) is reported in 30–50% of cases. Central nervous system (CNS) involvement outside the pituitary/hypothalamus carries a poor prognosis.

Case: A 36 year old Caucasian female presented with a 5 month history of a symmetrically distributed, red–brown papular rash affecting the eyelids, axilla and groin regions. The appearance of the rash was shortly followed by symptoms of polydipsia and polyuria. A water deprivation test with a vasopressin challenge was diagnostic of cranial DI. The patient responded well to vasopressin therapy. Cerebral MRI imaging demonstrated pituitary stalk thickening with no other cerebral involvement. Anterior pituitary function and prolactin levels were normal. Isotope bone scan was unremarkable. High resolution CT thorax did not demonstrate any granulomatous lesions. Histological examination of a skin biopsy showed a mixed spindled and epitheloid fibrohistiocytic lesion with scattered Tuoton - like giant cells compatible with a diagnosis of non - Langerhans cell histiocytosis. The lesions of Juvenile Xanthogranuloma (JX) histologically are indistinguishable from XD. Iron staining showed faint background positivity which has been described in XD.

Discussion: XD is a rare cause of cranial DI. Our case illustrates the challenge which may arise diagnosing XD and differentiating it from JX. In addition, it demonstrates the importance of correlating clinical features with histological findings in diagnosing the disease.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.