Indolent Progression of a Persistent Positron Emission Tomography (PET)-Negative Ground-Glass Pulmonary Nodule to Pulmonary Adenocarcinoma Following Nine Years of Radiographic Surveillance: A Case Report.

Indolent pulmonary adenocarcinoma spectrum lesions can remain radiographically stable for years and often demonstrate little to no fluorodeoxyglucose (FDG) uptake on positron emission tomography (PET), making diagnosis and management challenging. We report the case of a 74-year-old Caucasian woman with a remote five-year smoking history and a strong family history of lung cancer who was followed for a persistent right upper lobe ground-glass pulmonary nodule. Despite gradual enlargement, PET imaging performed seven years later demonstrated no significant FDG uptake. Serial computed tomography (CT) scans over the following years showed slow progression from a pure ground-glass nodule to a mixed ground-glass and part-solid lesion with an enlarging solid component, raising concern for an indolent adenocarcinoma. Transbronchial needle aspiration demonstrated atypical epithelioid cells, and immunohistochemical staining was positive for thyroid transcription factor-1 (TTF-1) and cytokeratin 7 (CK7) and negative for p40, confirming pulmonary adenocarcinoma. Repeat PET imaging two years later demonstrated mild FDG uptake despite histopathologic evidence of malignancy. This case highlights the prolonged radiographic evolution of a persistent ground-glass pulmonary nodule and demonstrates that limited FDG uptake does not exclude an indolent pulmonary neoplasm. Development or enlargement of a solid component within a persistent ground-glass nodule should prompt careful reassessment even when the metabolic activity remains low.