Update on the potential significance of psammoma bodies in lung adenocarcinoma from a modern aspect

Abstract

Aims

Psammoma bodies are concentrically lamellated microscopic structures of calcium. They are commonly observed in papillary carcinomas of the thyroid gland and serous papillary adenocarcinomas of the ovary, but are also occasionally detected in lung adenocarcinomas. Only one study has ever been published in 1972, which systematically described the significance of psammoma bodies in lung adenocarcinomas. We herein updated the significance of psammoma bodies in lung adenocarcinomas from a modern aspect.

Methods and results

Psammoma bodies were detected in 7.2% (59/822) of the adenocarcinomas examined, among which the papillary (20.3%, 12/59) or acinar (44.1%, 26/59) histological subtype with the feature of a terminal respiratory unit (91.5%, 54/59) was dominant. Malignant potential (cell growth activity measured by Ki-67 labeling, lymph node metastasis, and postoperative survival) did not significantly differ between adenocarcinomas with and without psammoma bodies. Based on cytogenetic features, adenocarcinomas with psammoma bodies were preferentially affected by tyrosine kinase inhibitors (TKI)-targetable driver mutations (EGFR (69.8%, 37/53), ALK (13.2%, 7/53), and ROS1 (1.9%, 1/53)). Multivariate analyses confirmed that psammoma bodies may be an independent predictor for these mutations, particularly EGFR and ALK.

Conclusions

Psammoma bodies may predict a favorable response of lung adenocarcinomas to TKI.

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