Primary pulmonary Hodgkin's lymphoma: A rare etiology mimicking pulmonary tuberculosis

Primary pulmonary Hodgkin's lymphoma (PPHL) is an extremely rare disease consisting of <1% of all lymphomas.1Radin A.I. Primary pulmonary Hodgkin's disease.Cancer. 1990; 65: 550-563Crossref PubMed Scopus (97) Google Scholar Diagnosis is challenging due to its non-specific clinical and radiological features. Here, we report a 16-year-old male that was noted to have an incidental finding of abnormal patch opacities in the left upper lung field from health examination chest X-ray (CXR). Clinically he had only experienced occasional dry cough in the morning in recent two months. He denied having fever, weight loss, shortness of breath, chest pain, exercise intolerance, and night sweating. He has neither contact history of infected tuberculosis (TB) nor family history of malignancy. He did not travel to foreign countries. Physical examination showed clear breath sounds without palpable lymph nodes or organomegaly. Laboratory workup showed leukocytosis (16,400 mm/L) with neutrophil predominant (77%) without anemia (Hemoglobin: 14.4 g/dL) and thrombocytopenia (platelet count: 315000/uL). Investigations for TB, including sputum culture, acid-fast stain, nucleic acid amplification test, and serum interferon-gamma release assay were all negative; however, pulmonary TB was still highly suspected, and a standard four-drug regimen was prescribed. CXR revealed progression of irregular nodular and patchy opacities over the left upper lung field despite two months of anti-TB therapy (Fig. 1A). Follow-up laboratory study showed persistent leukocytosis (24,000 mm/L) and an elevated C-reactive protein (CRP, 8.7 mg/dL). The chest computed tomography (CT) showed ill-defined patch consolidations with interlobular septal thickening and mild emphysematous change involving apical-posterior and anterior segments of the left upper lobe (LUL) (Fig. 1B). Differential diagnosis included pneumonia, congenital pulmonary airway malformation, and malignancy. Specimens from the diagnostic bronchoscopy with transbronchial biopsy and bronchoalveolar lavage still did not reveal any pathogen or malignant cells. Video assisted thoracoscopic surgery showed an inflamed LUL with severe adhesion to the chest wall. Therefore, pneumolysis and LUL lobectomy were performed. Pathological examination demonstrated pathognomonic Reed-Sternberg cell with single or multiple large nuclei and dense fibrotic band (Fig. 1C,D). Immunohistochemically, tumor cells were positive for cluster of differentiation (CD) 30, CD15, MUM1, and PAX5 with down regulation. Epstein–Barr virus-encoded small RNAs in situ-hybridization was also positive in tumor cells. Thus, PPHL nodular sclerosis type diagnosis was made. Chest, abdominal, pelvis CT, and brain magnetic resonance image showed no extra-thoracic tumors but a few subcentimeter lymph nodes in the paratrachea, subcarina, and left hilar areas. The final clinical stage is IIA confirmed by positron emission tomography scan. PPHL is a rare entity that is distinct from Hodgkin's lymphoma with parenchymal involvement, and few cases have been reported since the initial description in 1927.2El Hage H. Hossri S. Samra B. El-Sayegh D. Primary Pulmonary Hodgkin's Lymphoma: a rare etiology of a cavitary lung mass.Cureus. 2017; 9e1620PubMed Google Scholar Three criteria are required to make the diagnosis, which includes the following: (1) characteristic histological features of Hodgkin's lymphoma, (2) disease restriction to the lungs with or without minimal lymph node involvement, and (3) absence of extrapulmonary disease.3Cooksley N. Judge D.J. Brown J. Primary pulmonary Hodgkin's lymphoma and a review of the literature since 2006.BMJ Case Rep. 2014; 2014bcr2014204020Crossref PubMed Scopus (16) Google Scholar Our patient fulfilled all three criteria. PPHL presents common clinical and imaging features with many other pulmonary diseases, notably TB, thus, misdiagnosis is common.4Yang X. Xu X. Song B. Zhou Q. Zheng Y. Misdiagnosis of primary pleural DLBCL as tuberculosis: a case report and literature review.Mol Clin Oncol. 2018; 8: 729-732PubMed Google Scholar According to Yang's study,4Yang X. Xu X. Song B. Zhou Q. Zheng Y. Misdiagnosis of primary pleural DLBCL as tuberculosis: a case report and literature review.Mol Clin Oncol. 2018; 8: 729-732PubMed Google Scholar misdiagnoses may occur due to the following: (1) PPHL and TB share common symptoms such as fever, fatigue, and unexplained weight loss, (2) higher incidence of TB compared to extremely rare PPHL, especially in endemic areas, and (3) both PPHL and TB have predilection of the upper lobes. Here we report a case where CXR mimicked pulmonary TB. PPHL should be considered in differential diagnosis when lung nodular or cavitary lesions occur without microbiological diagnosis and poor response to anti-TB treatment, especially without contact or family TB history.5Aljehani Y. Al-Saif H. Al-Osail A. Al-Osail E. Multiloculated cavitary primary pulmonary Hodgkin lymphoma: case series.Case Rep Oncol. 2018; 11: 90-97Crossref PubMed Scopus (5) Google Scholar There was no conflict of interest.