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Histiocytic sarcoma in the bronchoalveolar lavage fluid

A 38-year-old male patient underwent bronchoalveolar lavage (BAL) after completing four cycles of chemotherapy for pulmonary histiocytic sarcoma. Six months previously, the patient presented to an outside institution for the evaluation of dyspnea, hemoptysis, fevers, night sweats, and unintentional weight loss. His medical history was significant only for hypertension, hyperlipidemia, and left-sided hearing loss. Imaging studies performed at that time, including chest X-rays and computed tomography (CT) scans revealed a dominant left upper lobe lung mass (Fig. 1) with scattered milliary lesions through the lungs, associated with mediastinal lymphadenopathy. A fluorodeoxyglucose positron emission tomography (F-FDGPET) scan showed a large hypermetabolic consolidation in the left upper lobe with hypermetabolic hilar and mediastinal lymphadenopathy. The differential diagnosis included an infectious versus neoplastic processes and the patient underwent transbronchial biopsies and fine needle aspiration of the dominant pulmonary lesion, which was diagnosed as histiocytic sarcoma of the lung (Fig. C-1). Wright-stained cytospin preparations, Papanicolaoustained smears from the cell pellet and hematoxylin-eosin-stained cell block sections were prepared from the BAL fluid. Cytologic evaluation showed numerous red blood cells, neutrophils, and eosinophils, occasional benign foamy macrophages, rare lymphocytes and mast cells, and scattered single large neoplastic cells in a background of amorphous granular necrotic debris. The malignant cells were round to polygonal in shape with amoeboid pseudopod-like cytoplasmic extensions, varied in size from 30 to 60 lm and had abundant cytoplasm. In Wright-stained preparations, the cytoplasm varied from light to dark blue and showed variable fine vacuolation (Fig. C-2). In Papanicolaou-stained smears, the cytoplasm ranged from gray to eosinophilic and from finely vacuolated to dense (Fig. C-3). In H&E-stained cell block sections, the cytoplasm was uniformly dense and brightly eosinophilic (Figs. C-4A and B). Neutrophils and occasionally lymphocytes were seen within the cytoplasm suggesting hemophagocytosis. The neoplastic cells contained one to four nuclei which varied in size from 15 to 25 lm, were round to ovoid or slightly indented and had smooth nuclear membranes, and vesicular or reticular chromatin. One to three very large irregular nucleoli measuring from 3 to 7 lm in greatest dimension were present and were sometimes surrounded by a thin clear halo. Some of the malignant cells appeared necrotic or mummified. No mitoses or apoptotic cells were identified. Immunoperoxidase stains showed that the large atypical cells were positive for lysozyme, CD68 (KP-1 and PGM1), CD4, CD45, and S-100 (Figs. 5C and D) and were negative for CD3, CD20, CD79a, CD15, CD30, myeloperoxidase, HMB-45, tyrosinase, and cytokeratin AE1/AE3. Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, Minnesota Division of Hematopathology, Department of Laboratory Medicine and Pathology, University of Minnesota Medical Center, Minneapolis, Minnesota Division of Surgical Pathology, Department of Laboratory Medicine and Pathology, University of Minnesota Medical Center, Minneapolis, Minnesota Division of Cytopathology, Department of Laboratory Medicine and Pathology, University of Minnesota Medical Center, Minneapolis, Minnesota *Correspondence to: Stefan E. Pambuccian, M.D., Department of Laboratory Medicine and Pathology, University of Minnesota Medical Center, Fairview, C422 Mayo MMC 76, 420 Delaware Street SE, Minneapolis, MN 55455. E-mail: pambu001@umn.edu Received 30 December 2011; Accepted 16 April 2012 DOI 10.1002/dc.22876 Published online 25 September 2012 in Wiley Online Library (wileyonlinelibrary.com).