Recurrent pneumothoraces, rash, and polyuria

Abstract

In October, 2008, a 23-year-old woman presented with sudden onset of left-sided chest pain and shortness of breath. She had a history of chronic cough with exertional dyspnoea for 2 years. She had been admitted twice to diff erent hospitals in the previous year for spontaneous pneumothoraces. She had refused further investigation and defaulted follow-up. She had been a smoker for 11 years. Over the previous year, she also noted itchy, nodular rashes aff ecting her armpits and vulva, as well as nocturia and polydipsia. Her primary care physician had managed her cough and rash symptomatically and reassured her that she did not have diabetes mellitus. On presentation, chest radiograph showed a left pneumothorax, so a chest tube was inserted urgently. Severe respiratory distress followed, and she was intubated. Examination showed ulcerative, nodular lesions aff ecting her armpits and vulva. She had notable polyuria with hypernatraemia (157 mmol/L). Desmo pressin was given, resulting in lower serum sodium (140 mmol/L); a diagnosis of cranial diabetes insipidus was made. MRI of the pituitary fossa showed thickening of the infundibulum. CT showed diff use cystic lesions in the lungs (fi gure A) and multiple small bony focal defects (fi gure B). Histological examination of skin lesion biopsy samples showed heavy infi ltrates of histiocytes with strong immunohistochemical staining to CD1a, confi rming the diagnosis of systemic Langerhans’ cell histiocytosis. She was successfully extubated on day 3 of admission and underwent a left thoracotomy for her pneumothorax, after which long-term corticosteroid treatment was started. When seen in February, 2009, she was no longer smoking, and her condition had improved. Her rash had subsided and the lesions seen on CT of the chest and bones remained stable. The aetiology of Langerhans’ cell histiocytosis is unknown, although smoking is the main risk factor for isolated pulmonary disease. Whether Langerhans’ cell histio cytosis is a neoplastic or reactive disorder is controversial. In contrast to paediatric Langerhans’ cell histiocytosis, which is monoclonal in nature, adult lung disease is polyclonal. The Histiocyte Society has developed a simplifi ed classifi cation system for adult Langerhans’ cell histiocytosis, consisting of single organ and multisystem involvement. The incidence in adults is around 1–2 cases per million with a mean age at diagnosis of 35 years. Up to a quarter of cases are asymptomatic. Presenting symptoms depend on the pattern of organ involvement, with bony pain, weight loss, and fever being the most common. Diabetes insipidus from pituitary involvement is a characteristic manifestation of the disease–as in our patient. Patients with lung involvement typically have non-productive cough and dyspnoea. The chest radiograph is usually abnormal, with bilateral reticulomicronodular infi ltrates being the most common pattern. High-resolution CT is mandatory in suspected cases of pulmonary Langerhans’ cell histiocytosis. Defi nitive diagnosis relies on demonstration of CD1a antigen on immunohistochemical studies or identifi cation of Birbeck’s granules on electron micrograph. Smoking cessation is essential in pulmonary Langerhans’ cell histiocytosis. Single organ disease can be managed with watchful waiting; multisystem disease may respond to corticosteroids and systemic chemotherapy. Most patients experience a favourable outcome, although isolated pulmonary Langerhans’ cell histiocytosis has the worst outcome. Lung transplant can be considered in advanced disease, but there may be recurrence in the allograft. Diagnosis of Langerhans’ cell histiocytosis is often delayed with a median time of 4 months. There was substantial delay in diagnosis in our patient, confi rming suboptimal awareness for this uncommon condition.