Desmoplastic small round cell tumor presenting as an atypical pneumonia: A case report

Introduction: Desmoplastic small round cell tumors (DSRCT) are aggressive sarcomas which primarily affect children and young adults. These tumors often remain asymptomatic until advanced stages, making early diagnosis and treatment challenging. Case presentation: We describe the case of a 14-year-old patient presenting with six months of persistent cough and dyspnea associated with a 30 kg weight loss. They were initially treated with antibiotics for suspected atypical pneumonia. Subsequent computed tomography (CT) imaging of the chest revealed bronchial thickening, mediastinal lymphadenopathy, a small pleural effusion, and sub-centimeter soft tissue densities in the left upper quadrant of the abdomen consistent with reactive lymph nodes. Bronchoscopy revealed diffuse mucosal abnormalities with airway pseudomembranes. Bronchoalveolar lavage (BAL) demonstrated rare fungal yeast forms with pseudo hyphae. Follow-up CT imaging revealed new right parietal pleural soft tissue masses, increased endobronchial plugging of the right middle and lower lobes, infiltrative changes of manubrium, sternum and liver, peritoneal implants, and extensive lymphadenopathy in the chest, abdomen, and pelvis. Diagnostic laparoscopy revealed significant ascites, matted omental lymph nodes, and peritoneal studding. Biopsies of omental lymph nodes and a peritoneal implant revealed desmoplastic small round cell tumor (DSRCT) with EWSR1:WT1 gene rearrangement. Chemotherapy was initiated. Despite radiographic and clinical evidence of response to therapy, the tumor burden remains unresectable. Conclusion: Given the significant morbidity associated with these tumors and the limitations on treatment options for advanced disease, sarcomas should be included in the differential diagnosis for any child or adolescent who does not respond to treatment for atypical pneumonia.