A unique case of pulmonary minimally invasive mucinous adenocarcinoma arising from atypical goblet cell hyperplasia in the bronchial epithelium of a 9-year-old girl

Abstract

Background: Pulmonary mucinous adenocarcinoma without congenital pulmonary airway malformation (CPAM) is extremely rare in pediatric patients. Here, we report a unique case of minimally invasive mucinous adenocarcinoma without CPAM in a child and provide a comprehensive review of the clinical, radiographic, and histopathological characteristics of the published literature.

Case presentation: A 9-year-old girl presented with persistent cough and sputum production, raising suspicion of respiratory infection. Chest computed tomography (CT) revealed a solid nodule measuring 1.9 cm × 1.6 cm in the right lower lobe. Prenatal ultrasonography revealed no congenital lung abnormality. The patient subsequently underwent video-assisted thoracoscopic surgery (VATS) without postoperative complications. Histologically, a focal area demonstrated marked atypical goblet cell hyperplasia in the bronchial epithelium, which abruptly transitioned to mucinous adenocarcinoma, predominantly characterized by a lepidic growth pattern and extensive extracellular mucin accumulation. Pathological examination confirmed pulmonary minimally invasive mucinous adenocarcinoma, staged as pT1miN0M0. Next-generation sequencing (NGS) identified the KRAS G12D mutation. The patient remained well 11 months after resection and did not require additional treatment.

Conclusions: We demonstrated a novel stepwise progression originating from atypical goblet cell hyperplasia in the bronchial epithelium, rather than from the CPAM, in a pediatric patient. KRAS mutations may play a critical role in the development of pulmonary mucinous adenocarcinoma in pediatric patients.

Keywords: Minimally invasive mucinous adenocarcinoma; Pediatric oncology; Pulmonary adenocarcinoma; VATS.

Fig. 1

Radiological, histopathological, and immunohistochemical features of pulmonary minimally invasive mucinous adenocarcinoma. Chest CT revealed a solid nodule measuring 1.9 cmx1.6 cm in the posterior basal segment of the right lower lobe (A, arrow) with irregular margins and slight enhancement (B, arrow). The resected tumor specimen showed a predominantly lepidic pattern with mucous secretion under low-power view (C). Middle-power magnification revealed tumor cells with abundant apical cytoplasmic mucin and small, basally oriented nuclei growing along the surface of the preserved alveolar walls (D). The partial tumor exhibited an invasive pattern of infiltrative glands lined by tumor cells containing abundant intracytoplasmic mucin (E). The focal area exhibited atypical goblet cell hyperplasia (F, arrows) in the bronchial epithelium (F, triangles). (Magnification x100). Immunohistochemical analysis revealed positive staining for CK7 (G) and negative staining for TTF-1 (H). CK5/6 staining revealed no evidence of basal cell layer (I). (Magnification ×100)