WCLC 2025 - Posters & ePosters-EP.04.21 Imaging Manifestations in 4 Cases of Invasive Pulmonary Adenocarcinoma With Indolent Growth

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This study reports imaging and clinical features of four cases of invasive pulmonary adenocarcinoma characterized by indolent (slow) growth. All patients (three females, one male; mean age 57) had peripheral lung carcinomas diagnosed via CT imaging and pathology confirming invasive adenocarcinoma, with either solid or solid-predominant nodules (>90% solidity).<br /><br />A key imaging finding common to all cases was a clear "5-line sign" observed on maximum intensity projection (MIP) CT reconstructions, based on the presence of a pleural tail sign at the nodule edge. The 5-line sign consists of five distinct smooth contour lines with clear intervals, believed to reflect tumor interactions with the pleura and adjacent structures. Previous literature suggests this sign is predictive of tumor invasiveness, progression, and prognosis.<br /><br />Tumor volume doubling times (VDT) were notably prolonged, averaging 1994 days (range 1593-2485), indicating extremely slow tumor growth compared to typical solid lung cancers where doubling time averages 207 days. Additional imaging features included vacuoles and air-bronchograms within the tumors, also associated with slow-growing adenocarcinomas. Long-term follow-ups (4-10 years) after surgery showed no recurrence or metastasis.<br /><br />Cases described include: a female with a right upper lobe nodule undetected by chest x-rays for years until CT identified the lesion showing characteristic signs; a male with a left lower lobe nodule that enlarged slowly over seven years before resection; a female with an acinar-predominant tumor treated non-surgically with stable disease for several years; and a female whose nodule was overlooked during initial infection treatment but later identified with typical signs and confirmed as adenocarcinoma upon later resection.<br /><br />The authors conclude that a distinct 5-line sign on MIP reconstructions, combined with pleural tail and internal tumor features, may serve as a meaningful imaging marker for indolent invasive adenocarcinomas. Such tumors are associated with slow progression and favorable prognosis, supporting the utility of these imaging signatures in clinical assessment and management planning.

Asset Subtitle

Anle Yu

Meta Tag

Speaker Anle Yu

Topic Screening and Early Detection

Keywords

invasive pulmonary adenocarcinoma

indolent tumor growth

5-line sign

maximum intensity projection CT

pleural tail sign

tumor volume doubling time

vacuoles in tumors

air-bronchogram

slow-growing lung cancer

imaging markers for prognosis