A previously healthy 12-year-old boy presented with multiple episodes of upper gastrointestinal bleeding over four days. He denied abdominal pain, melena, jaundice, fever, or urinary changes. Family and social history were unremarkable. Upper GI endoscopy revealed hyperemic gastric fundal spots without active bleeding. However, persistent bleeding was noted from the Endotracheal Tube (ETT) during the procedure.

Following stabilization, flexible bronchoscopy revealed inflamed airways with a large obstructive clot in the right intermediate bronchus. As depicted in the Chest CT (Figure 1) demonstrated right lower lobe collapse with a "tree-in-bud" appearance, suggesting possible infection or hemorrhage. A CT angiogram raised suspicion of right lower lobe pulmonary sequestration (Figure 2).

A multidisciplinary team—including pediatric surgery, thoracic surgery, pulmonology, PICU, and gastroenterology—determined the need for urgent bronchoscopy and possible lobectomy due to ongoing hemorrhage. Medical management, including transfusion of blood products, failed to stop the bleeding. Chest radiography showed complete right lung opacification, likely due to airway obstruction.

The thoracic team proceeded with rigid bronchoscopy, identifying and removing friable granulation tissue and fresh clots from the right lower lobe bronchus. Despite those measures, bleeding persisted, prompting immediate thoracotomy and right middle lobectomy. Intraoperatively, a mass was found at the upper part of the right lower lobe extending into the middle lobe, necessitating careful resection of the right lower lobe up to but preserving the right middle lobe and bronchus (Figure 3).

Intraoperatively, the patient experienced sudden desaturation due to a dislodged fatty tissue fragment obstructing the left main bronchus, which was successfully removed using Dormia basket. The patient stabilized and had an uneventful recovery in the PICU. He was discharged home in a stable condition on day 10 postoperatively.

Histopathological examination revealed low-grade bronchial mucoepidermoid carcinoma (Figure 4a,4b,4c). It showed a malignant epithelial neoplasm composed predominantly of invasive carcinoma with focal squamous differentiation and mucin-secreting cells, set within a background of cystic spaces and focal solid areas. A small high-grade component, comprising less than 10% of the overall tumor volume, demonstrated solid and nested architecture, cytological atypia, increased mitotic activity, necrosis, and hemorrhage (Figure 4).

Immunohistochemical analysis showed the tumor cells were positive for Pan-Cytokeratin (Pan-CK), Cytokeratin 7 (CK7), and focally positive for CK5/6 and p63 [5]. The tumor cells were negative for TTF-1, Napsin A, Synaptophysin, Chromogranin, CD56, CD10, GATA-3, p16, Melan-A, S100, and Progesterone Receptor (PR). Mucicarmine stain highlighted the mucin-secreting component. The Ki-67 proliferation index was approximately 4%. The histomorphological features, together with the immunohistochemical profile, support a diagnosis of low-grade mucoepidermoid carcinoma, likely originating from bronchial submucosal glands, with a focal high-grade component (<10%). Hilar lymph node biopsy showed no evidence of LN involvement.

Accordingly, the Pathologic Stage Classification (pTNM, AJCC 8th Edition) was pT1b pN0.

Post-surgical imaging revealed residual heterogeneously enhancing soft tissue at the bronchus intermedius and enlarged paratracheal nodes. The patient was referred for oncology center for PET scan, chemotherapy and close follow-up. Fortunately, after PET scan the patient needed no further treatment.