Abstract / Summary
Invasive mucinous adenocarcinoma (IMA) is an uncommon histological subtype of lung adenocarcinoma that can mimic pneumonia or other inflammatory lung diseases due to its distinct radiological features.Although multifocal consolidations, nodules, and masses are frequently observed, cavitation is relatively uncommon.These atypical radiological findings can complicate diagnosis and delay treatment.We present a case of a lifelong never-smoker in her late 60s who presented with chest pain and productive cough, a history of two recently treated chest infections, and significant weight loss.Laboratory evaluation showed elevated C-reactive protein (CRP) with normal procalcitonin and white blood cell count.Chest imaging revealed widespread bilateral consolidations, nodules, cavitation, and traction fibrosis, a pattern considered atypical for conventional lung malignancy and initially more suggestive of granulomatous disease or atypical infection.Extensive infectious, fungal, and autoimmune screening, along with serum angiotensinconverting enzyme level, did not identify an alternative cause.Bronchial wash and bronchoalveolar lavage (BAL) were non-diagnostic.Persistent symptoms and radiological abnormalities despite initial work-up ultimately led to CT-guided tissue biopsy of the lung, which confirmed the diagnosis of IMA.Further immunohistochemistry supported a primary pulmonary origin.Comprehensive molecular profiling did not reveal any clinically actionable driver alteration; therefore, she was commenced on first-line chemoimmunotherapy with carboplatin, pemetrexed, and pembrolizumab.She remains clinically stable and is tolerating treatment without dose-limiting toxicity; objective radiological response has not yet been assessed.This case highlights that persistent bilateral consolidations, nodules, cavitation, and fibrotic changes may occasionally represent an unusual presentation of lung malignancy, including IMA, even when infection or granulomatous disease is initially considered.Persistent radiological abnormalities despite negative microbiological and bronchoscopic investigations should prompt reconsideration of the differential diagnosis, even in lifelong never-smokers, with early tissue biopsy playing a pivotal role in establishing the diagnosis.