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Correspondence to Author: Richard Ott¹, Yunfei Wei¹,, Hung-I Liao¹, Beverly Wang², Terry M Welsh^1,3,4, Lei Zhang^1,3,4. 

1. Anaheim Regional Medical Center, Anaheim, California, USA.
2. University of California at Irvine, California, USA.
3. Pathology Associates of Anaheim, Anaheim, California, USA.
4. Parkview Community Hospital Medical Center at riverside, California, USA

DOI: 10.52338/tclc.2025.4716

Abstract:

Background:Pulmonary sclerosing pneumocytoma (PSP) is a rare solitary benign tumor. The unusual multifocal presentation creates a big challenge in diagnosis and management. We report such a case, linking the spectrum morphology of multiple evolving PSP to a novel genetic change for the first time.
Case presentation: A 47-year-old asymptomatic, non-smoker female presented with incidental 14 bilateral lung nodules. The initial biopsy strengthened the clinical suspicion of metastatic lung adenocarcinoma. However, no extrapulmonary involvement was detected and the liquid biopsy was also negative. The left upper lobectomy was performed for a definitive diagnosis. This has led to a pathological finding of seven PSP tumors, with the largest 3 cm mass showing characteristic solid, papillary, hemorrhagic and sclerotic patterns, and five smaller nodules showing a spectrum morphology of PSP starting from pneumocytes hyperplasia, evolving to four histological patterns and ended with fibrosis. Somatic Fibroblast Growth Factor Receptor 3 (FGFR3) pE360K mutation is present in the tumors and background lung parenchyma. While additional AKT1 internal tandem duplication (p.R67_L78 dup), which is a known hallmark for PSP, is limited to the largest mass. No other driver gene mutations classic for lung cancer are detected among over 2000 genes examined. Patient is free of recurrence or metastasis during two-year follow up.
Conclusion: The diagnosis of PSP could be difficult in small biopsy and frozen. Synchronous presentation of PSP is attributable to the somatic mutation of FGFR3 (pE360K). Secondary AKT abnormality promotes tumor growth but does not change the benign course of PSP in this case.
Keywords: FGFR3, multifocal pulmonary sclerosing pneumocytoma, AKT1.

Citation:

Dr.Lei Zhang, Multifocal Pulmonary Sclerosing Pneumocytomas Mimicking Adenocarcinoma Associated With Somatic FGFR3 Mutation: A Case Report. The Clinical Lung Cancer 2025.