INTRODUCTION: Malignant histiocytosis is a rare disease that can proliferate systemically, but even more rare to involve the lungs. We present a case of a patient with submental lymphadenopathy and bilateral pulmonary nodules, both identified as malignant histiocytosis by tissue sampling.
CASE PRESENTATION: An 84 year old male lifetime non-smoker with a history of prostate cancer presented with enlarging neck mass and worsening dyspnea. He had fevers, weight loss, night sweats, non productive cough and diarrhea for the past 3 months. He had a computed tomography (CT) of his neck showing a hypodense mass and a chest CT showing multiple bilateral pulmonary nodules. On exam, he had a nontender left neck mass, submental lymphadenopathy and unremarkable lung exam. His laboratory findings included anemia, low serotonin, normal prostate specific antigen and carcinoembryonic antigen levels. He had a serum protein electrophoresis with a small monoclonal band present in the gamma region. Immunofixation had biclonal gammopathy of IgG kappa and lambda. Urine protein electrophoresis did not show abnormal peaks. He had a fine needle aspiration of the neck mass that showed undifferentiated malignant cells, but did not get characterized by immunohistochemistry. This was followed by further tissue investigation with an excisional biopsy of the submental node that showed a malignant hematopoeitic tumor and characterized by immunohistochemistry (CD4, CD38, CD43, CD 68 and S100) as malignant histiocytosis. There were no Birbeck granules of Langerhans Histiocytes seen on electron microscopy. A bronchoscopy with bronchoalveolar lavage, transbronchial needle aspiration of right hilar lymph node and transbronchial biopsy of right middle and lower lobes showed pathology of malignant histiocytosis and confirmed with immunohistochemistry. He was started on treatment with dexamethasone followed by vinblastine therapy. His dyspnea was eventually controlled.
DISCUSSIONS: Malignant histiocytosis is a rare invasive proliferation of histiocytic and dendritic origin involving lymph nodes, bone marrow, spleen, liver, but can also involve brain and lung. Constitutional symptoms are common with fevers, night sweats and weight loss. Pulmonary involvement includes nodules, infiltrates, pleural effusion and bronchoesophageal fistula. Immunohistochemistry is positive for CD68, lysozyme, CD11c, CD14 and S100, but lacks CD1a and no Birbeck granules will be seen on electron microscopy that differentiates it from Langerhans cell histiocytosis. Recent histopathological combined with genotypical and immunophenotypical evidence, malignant histiocytosis corresponds to anaplastic large cell lymphoma of B and T cell types. Given its rare occurrence, diagnosis remains difficult. Treatment has historically involved corticosteroids, etoposide, intravenous immunoglobulins and immunosuppressive agents with an anticipated response of longer survival and clinically stable disease.
CONCLUSION: Malignant histiocytosis is a rare cause of pulmonary nodules. Diagnosis of malignant histiocytosis remains difficult because of its rarity. Careful attentive examination of cytologic features might help with the diagnosis. Immunohistochemical advancements will further help characterize these tumors.
DISCLOSURE: Eldrige Pineda, Other Eric D. Anderson, Educational honoraria from Accuray, Consultant for SuperDimension and Bronchus; No Product/Research Disclosure Information