To analyze the CT imaging characteristics, clinicopathological features, diagnosis and differential diagnosis of minute pulmonary meningothelial-like nodules (MPMNs).

A total of 42 patients with MPMN diagnosed in our hospital from December 2020 to January 2023 were selected. Retrospective analysis of the CT imaging features, histomorphological manifestations. Expression of SSTR2, PR, Vimentin, EMA, CD56, CK (AE1/AE3), TTF-1, CgA, Syn, SMA, Ki-67 was detected by immunohistochemical EnVision method and the relevant literature was reviewed.

In 42 cases, 23 cases were associated with pulmonary precursor adenopathy and malignancy, 8 cases with benign pulmonary lesions and 11 cases without concomitant lesions. High-resolution CT showed scattered to multiple microscopic nodules in both lungs in addition to the main lesion in 42 patients, and post-operatively multiple MPMN were found in 10 cases and single in 32 cases, with lesion sizes <1.0 cm. Both intraoperative frozen sections and paraffin sections showed widened alveolar septa with mild epithelioid and spindle cells proliferating in clusters along the interstitium with indistinct cell borders forming a syncytial pattern, round or ovoid nuclei, inconspicuous nucleoli, moderate cytoplasm, lightly stained, rare nuclear schizophrenia, and intra-nuclear pseudo-inclusion bodies. Immunohistochemical results were positive for SSTR2 (21/21) and vimentin (29/29), positive for PR (28/29), positive for EMA (28/32), positive for CD56 (18/21), and negative for ER, CK (AE1/AE3), TTF-1, CgA, Syn, and SMA were all negative, Ki-67 positivity index was<1%.

MPMN occurs in middle-aged and elderly women, with small lesion diameters, and most MPMN may be multiple lesions. The cell morphology and immunophenotype are similar to meningiomas, and the diagnosis is supported by positive immunohistochemical markers SSTR2, PR, CD56, and EMA.