Pulmonary involvement is present in approximately 25% of children with multisystem low-risk and high-risk LCH. However, a multivariate analysis of pulmonary disease in multisystem LCH did not show pulmonary disease to be an independent prognostic factor, with a 5-year overall survival rate of 94% versus 96% for those with or without pulmonary involvement.
Most patients with bone marrow involvement are young children who have diffuse disease in the liver, spleen, lymph nodes, and skin who present with significant thrombocytopenia and anemia with or without neutropenia. Others have only mild cytopenias and are found to have bone marrow involvement with LCH by sensitive immunohistochemical or flow cytometric analysis of the bone marrow. All of the bone marrow biopsy specimens (22 of 22 specimens) in one study had increased numbers of dysplasia of megakaryocytes, often with emperipolesis (active penetration by one cell into and through a larger cell). Patients with LCH who are considered at very high risk sometimes present with hemophagocytosis involving the bone marrow. The cytokine milieu driving LCH is probably responsible for the epiphenomenon of macrophage activation.
Diabetes insipidus, caused by LCH-induced damage to the anti-diuretic hormone (ADH)–secreting cells of the posterior pituitary, is the most frequent endocrine manifestation in LCH. MRI scans usually show nodularity and/or thickening of the pituitary stalk and loss of the pituitary bright spot on T2-weighted images. Pituitary biopsies are rarely done and usually only when the stalk is greater than 6.5 mm or there is a hypothalamic mass. Most often the diagnosis is established by biopsying the skin, bone, or lymph node of a patient who also has pituitary abnormalities.
Approximately 4% of patients present with an apparently idiopathic presentation of diabetes insipidus before other lesions of LCH are identified, 7% concomitantly with another location and 14% after extrapituitary diagnosis of LCH. A report of 26 patients who presented with isolated diabetes insipidus as the initial manifestation of LCH described their natural history. Eleven of the patients presenting with isolated central diabetes insipidus also had anterior pituitary deficits. These included secondary amenorrhea, panhypopituitarism, growth hormone deficiency, hypoadrenalism, and abnormalities of gonadotropins. Twenty-two of the 26 patients ultimately developed extrapituitary lesions of LCH, including bone (n = 15), lung (n = 9), and skin (n = 9), in a median time of 1 year (range, 1 month to 14.2 years).