OCCULT PRESENTATION OF ADULT LANGERHANS CELL HISTIOCYTOSIS WITH EXTRAPULMONIC MANIFESTATIONS

Abstract

INTRODUCTION: Adult Langerhans Cell Histiocytosis (LCH) is a rare interstitial lung disease most commonly of smokers in their 3rd and 4th decade. Clinical presentation is often one of non specific respiratory complaints and constitutional symptoms with cysts and nodules in the upper lung zones on chest radiography. Twenty percent of patients present asymptomatically with incidental findings on a chest film. Pulmonary complications of LCH include spontaneous pneumothorax, pulmonary arteriopathy and veno-occlusive disease, and pulmonary hypertension. Extrapulmonary manifestations include central diabetes insipidus (DI), skeletal, mucocuteanous, hepatic, splenic, lymph node, or marrow involvement. Although adult LCH is often considered a pulmonary disease, it can present with only extrapulmonic manifestations. We describe the case of an adult male with preexisting 'idiopathic' central DI and a new occipital skull lesion. CASE PRESENTATION: A 45 year old male with central DI and a 25 pack year smoking history presented to his family physician with a recent onset of headaches, visual changes, and a self-described scalp deformity in the occipital region. He denied cough, chest pain and dyspnea but did have fever and night sweats. Imaging (MRI and CT) of his head 2 years prior revealed only a pituitary microadenoma. Repeat MRI revealed interval development of a multiloculated cystic mass in the occipital bone involving both the underlying dura and the overlying subcutaneous tissues. Chest radiograph was normal. Because of the broad differential diagnosis including osteomyelitis, multiple myeloma, lymphoma, and metastatic disease, the lesion was surgically excised. Pathology identified LCH. With the diagnosis of LCH, further investigations were completed. Pulmonary function tests showed normal spirometry, normal lung volumes and decreased DLCO. Despite previously normal chest radiographs, a CT chest showed small bilateral cysts and nodules in the upper and mid lung zones. Further history of pain and parasthesia in his left leg was identified and a CT scan identified a lytic lesion in the left iliac crest. A bone scan confirmed this lesion as well as lesions in the left humerus and right sixth rib. Treatment was initiated with vinblastine, steroids and 6-mercaptopurine as per the LHC-III protocol. At one year of follow-up he had persistent central DI, was free of calvarial disease, but had persistence of both pulmonary and bony lesions. An allogenic stem cell transplant was considered a treatment option for progressive disease. DISCUSSIONS: LCH is a multisystem disease that is often is primarily thought of as a lung disease in adults causally related to smoking. When patients present only with extrapulmonic manifestations in the absence of pulmonary symptomatology, the diagnosis of LCH may easily be overlooked. For this reason LCH has been previously described as an orphan disease as initial presenting lesions may not be recognized as part of a systemic process. As the disease is rare in adults it is difficult to link the clinical features to identify disease prognosis, optimal therapy and natural history of the disease. The disease is classified into single or multi system disease with involvement of risk (lung, liver, spleen, marrow) organs. In this case, with involvement of occipital bone and surrounding soft tissues, 3 other bony sites, central diabetes insipidus, and lung involvement, this is multisystem disease involving a 'risk' organ. Optimal treatment and expected response to therapy is still not well known. CONCLUSION: We have described a case of LCH that presented with central DI and a skull lesion. A greater awareness of LCH and its various clinical presentations is required to ensure that the diagnosis can be made.