ESPE Abstracts

Langerhans cell histiocytosis (LCH) is a rare disorder of unknown etiology affecting the mononuclear phagocyte system. It is characterized by clonal uncontrolled proliferation and accumulation of immature dendritic cells in different organs. Affected cells express CD1-alpha and/or CD207 (Langerin) on immunohistochemistry. Although bone is the most commonly affected organ (80%), all other organs can be affected either alone or in combination. LCH is classified into Single system (SS) or Multisystem (MS). MS-LCH carries a worse prognosis and is classified into "with risk organ as liver, spleen or bone marrow" or "without risk organ". Classically, Hypothalamic pituitary axis (HPA) affection is commonly associated with multisystem severe disease leading to Central Diabetes Insipidus and less commonly Anterior pituitary deficiencies. In this case we present a case of Isolated HPA-LCH that presented primarily with short stature. An 11.5 year old male presented with proportionate short stature and no dysmorphic craniofacial features. We found central hypothyroidism and severe Growth hormone deficiency by two different provocation tests (Peak 0.8 and 0.9). Water deprivation test revealed central diabetes insipidus. ACTH and cortisol at 8 am and 8 pm were found normal. MRI sella tursica with contrast revealed: absent posterior pituitary gland bright spot and diffuse thickening of the pituitary stalk with intense post contrast homogenous enhancement. The radiological findings pointed us to the diagnosis of pituitary LCH. Differential Diagnosis included germinoma or primary lymphoma. Whole body scan using TC-99 showed no bone involvement. Although biopsy was not feasible, the patient follow up in the oncology department excluded the possibility of a neoplasm. Genetic testing for LCH was not possible owing to the high cost and unavailability. MRI sella was repeated after 1.5 years, showing a stationary course of the same lesions and confirming the diagnosis LCH. We started treatment with Minirin and thyroid hormone after the initial investigations. Growth Hormone was added after 2 years of follow up. 18 months later, we observed recognizable increase in growth velocity and no deleterious effects on LCH disease activity.

Conclusion: Although rare, isolated HPA-LCH can present primarily with short stature as part of panhypopituitarism. Therefore, any case of GH deficiency should be thoroughly investigated for an underlying cause.