Objectives: Invasive mucinous adenocarcinoma (IMA) is a variant of lung adenocarcinoma with several growth patterns, such as lepidic acinar and papillary. However, to our knowledge, no study regarding prognostic and clinicopathologic aspects of IMAs with different growth patterns has been reported.
Methods: Of 2,236 patients with primary lung adenocarcinoma, 16 were identified as having lepidic-predominant IMA and 10 as having acinar-predominant IMA. Data regarding the clinicopathologic characteristics, computed tomography (CT) features, and prognosis were collected.
Results: No statistically significant difference was noted in sex, age, smoker proportion, and T classification between both groups. The proportion of lymph node metastasis was significantly higher in acinar-predominant IMA (P = .046). Both groups shared many signs in CT findings. Air bronchogram was a relatively specific sign for lepidic-predominant IMA. Survival analysis showed that acinar-predominant IMA had a poorer prognosis (P = .0294).
Conclusions: Lepidic-predominant and acinar-predominant IMA are two different subtypes of IMA. Acinar-predominant IMA is associated with lymph node metastasis and a poorer prognosis.