Pulmonary Histoplasmosis Producing a Spindle Cell “Pseudotumor”

Abstract

Pulmonary spindle cell proliferations have been reported in association with a limited group of infectious agents. These lesions are rare and identified most often in the setting of immunosuppression. Because their appearance can simulate a spindle cell neoplasm, they are diagnostically treacherous, sometimes delaying antimicrobial therapy or resulting in unnecessary surgery. We report a case of a spindle pseudotumor of the lung resulting from Histoplasma capsulatum infection, a previously unreported cause of a spindle cell lesion in the lung. The patient was a 67-year-old woman in whom positron emission tomography-positive nodules developed in the left lung and left mediastinum. The patient had undergone renal transplantation and was receiving immunosuppressive therapy with mycophenolate, tacrolimus, and low-dose prednisone. Infection with H capsulatum was confirmed by culture of pleural effusion fluid, DNA probe analysis of the pleural fluid culture isolate, urinary Histoplasma antigen detection, and Grocott methenamine silver stains of tissue sections. To our knowledge, this is the first case of a spindle cell "pseudotumor" of the lung resulting from histoplasmosis. It highlights the importance of performing special stains for organisms when evaluating pulmonary spindle cell lesions in an immunocompromised host.

Syphilitic Pulmonary Inflammatory Pseudotumor: A Diagnostic Challenge

“…7 In this location also, a number of different organisms have been implicated, including mycobacteria, Coxiella , Histoplasma , and Cryptococcus . 8 -11…”

“…7 In this location also, a number of different organisms have been implicated, including mycobacteria, Coxiella, Histoplasma, and Cryptococcus. [8][9][10][11] Syphilis is a chronic disease caused by Treponema pallidum and is usually transmitted by sexual contact, from mother to child and rarely by blood-borne infection. If untreated, syphilis has a long progressive natural history consisting of primary, secondary, and tertiary stages.…”

Pulmonary mycobacterial spindle cell pseudotumor in a lung transplant patient: progression without therapy and response to therapy

“… reported a case of MSP of the nasal cavity in which nasal swabs for mycobacterial cultures were negative, but acid‐fast tissue stains yielded the correct diagnosis. Although acid‐fast staining of biopsy tissue in immunocompromised patients is clearly valuable, reports of MSP describe occasional cases involving non‐diagnostic acid‐fast staining in which the diagnosis required tissue culture or polymerase chain reaction‐based detection , or the inciting infection was ultimately identified as fungal rather than mycobacterial . In our case, acid‐fast staining and culture both implicated MAC as the causative agent.…”

“…Ziehl–Neelsen staining for acid‐fast mycobacteria allows for the diagnosis of MSP in cases where this diagnosis may not otherwise be suspected. Notably, MSP caused by Histoplasma capsulatum has also been described .…”

Histoplasmosis in transplant recipients

“…Radiologic findings are nonspecific and include multiple pulmonary nodules, mediastinal and perihilar lymphadenopathy, cavitary lesions, diffuse bilateral infiltrates, and occasionally military pattern . Pleural effusion with positive fungal culture or histoplasma antigen in the pleural fluid has also been reported . CT of the abdomen may also reveal splenomegaly and lymphadenopathy in 50% cases of disseminated histoplasmosis .…”