A Rare Case of Diffuse Bilateral Minute Pulmonary Meningothelial-like Nodules Increasing over the Short Term and Resembling Metastatic Lung Cancer

Abstract

A 54-year-old woman was referred to our hospital because computed tomography (CT) revealed multiple lung nodules during a health checkup. The nodules were up to 5 mm in diameter and randomly distributed in both lungs, appearing ring-shaped. No clinical symptoms were present. However, the nodes proliferated, and multiple lung metastases could not be ruled out, so a biopsy was performed to establish a diagnosis. She was diagnosed with minute pulmonary meningothelial-like nodules (MPMNs), and her condition had not deteriorated at the latest follow-up. Although rare, MPMNs can proliferate for a short time, but a biopsy to exclude malignant causes is essential.

Keywords: increasing nodules; mimicking metastatic lung cancer; minute pulmonary meningothelial-like nodules; pulmonary chemodectoma.

Figure 1.

Chest computed tomography (CT) showed diffuse bilateral minute ground-glass opacities on initial consultation. The nodules were randomly distributed, measuring up to 5 mm in diameter, and some had central lucency (A, B). The number of nodules increased four months later (C).

Figure 2.

Pathological findings. Spindle-shaped cells with lightly acidic vesicles and round nuclei proliferated along the alveolar septum. Immunohistochemical staining of the cells was positive for vimentin and progesterone receptors.

Figure 3.

Chest CT confirmed the presence of minute nodules four months prior to a surgical lung biopsy (SLB; green arrows). At the time of the SLB, an increased number (yellow arrows) and slight enlargement of some nodules (green arrows) were observed. Six months after the SLB, the size of the nodules remained unchanged (green and yellow arrows), but the number of nodules increased (red arrows). Twelve months after the SLB, there was no marked increase in the number or size of nodules (green, yellow and red arrows).