Multisystem Langerhans Cell Histiocytosis in an Infant With Pulmonary Involvement at Onset, Not Everything is Tuberculosis in Latin America – A Case Report

Abstract Introduction Langerhans cell histiocytosis (LCH) is a rare hematological disease occurring in 2.6 to 8.9 per million children under the age of 15 and with a median age of 3 years. Multisystem LCH (MLCH) carries a survival rate of up to 65 to 73%. We present a case of a 14-month-old patient with systemic high risk LCH and significant pulmonary involvement mimicking the clinical presentation of disseminated Tuberculosis (TB). Case presentation A 14-month-old boy presented with a 4-week history of sweating, poor appetite, intermittent fever, failure to thrive, and respiratory symptoms and skin lesions in the last 10 days. At presentation he was found to have subcostal retractions, bilateral basal crackles, hepatosplenomegaly, generalized painful lymphadenopathy and hypoxic. Laboratory findings showed microcytic hypochromic anemia and raised inflammatory markers. Ultrasound imaging revealed multiple cervical and axillary lymphadenopathies with loss of the fatty hilum, hypoechoic nodules within the parotid gland, hepatosplenomegaly, aortomesenteric lymphadenopathy and mild pulmonary hypertension. High-resolution tomography chest showed randomly distributed pulmonary nodules, some with cavitations, cystic spaces, and some areas of tree-in-bud pattern. A bronchoalveolar lavage isolated Haemophilus influenzae and was found to be positive for Pneumocystis jirovecii. Extensive testing was found to be negative for TB. Histology findings from pulmonary nodule and lymph node biopsies showed histiocytoid cells and multinucleated giant cells, with immunohistochemistry positive for S100, CD1a, and langerin markers. LCH 2014 treatment protocol was initiated. Following this a whole-body resonance showed persistent extensive multisystem involvement for which the patient was initiated on Clofarabine and Mercaptopurine. However, pulmonary involvement continues to persist. Whilst a targeted exome analysis was negative for causal mutations, a complete analysis is pending.Discussion In Colombia, TB is a condition of moderate endemicity and a significant differential diagnosis for this clinical presentation; however this case highlights the importance of considering other diagnoses. Whilst pulmonary involvement is common in MLCH, isolated pulmonary involvement and extensive respiratory symptoms are rare in children. This presentation is associated with complications such as spontaneous pneumothoraces, pulmonary fibrosis and restrictive lung disease. Management of this condition involves systemic chemotherapy and Cladribine as a second-line treatment, however due to lack of availability, Clorafabine was used instead. Conclusion Whilst LCH is a rare condition, it is an important differential diagnosis in this clinical presentation. It can easily be misdiagnosed as TB, and for both conditions, diagnostic timing is fundamental to determine survival and prognosis of any pulmonary progression.