PMC9345627_01
Typical thin-section CT presentation of MPMNs. Multiple ground glass density shadows in the middle and lower lobes of the left and right lungs (shown in red boxes), 0.2-0.4 cm in diameter, with irregular shadows and slightly blurred boundary. (A-D) show ground glass density nodules in left and right lungs at different CT sections.
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Imaging manifestations: multiple micronodules, mostly ground glass density nodules, were seen on chest CT ( Figure 1 ).
Morphological characteristics of intraoperative frozen sections of MPMNs. (A) Frozen section HE staining x7.2. Three nodules (shown in the red box) with irregular morphology and clear borders are visible in the lung tissue. (B) x40 shows 1 of the nodules growing around the blood vessels. (C) Frozen section, HE staining, x100. The lesion cells are growing along the alveolar septum, with an open air cavity and the proliferation of interstitial fibrous tissue. (D) Frozen section, HE staining, x200. Well-differentiated cells were observed without atypia, with a smooth nuclear membrane, a low nucleo-cytoplasmic ratio and no pathological nuclear division.
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Only 1 case was diagnosed as a benign lesion, and the typing was pending postoperative paraffin section results, while the other 6 cases were all diagnosed as atypical alveolar epithelial hyperplasia pending postoperative paraffin section results ( Figure 2 ).
Morphological characteristics of postoperative paraffin sections of MPMNs. (A) Paraffin section HE x7.2 with an open alveolar cavity, uniform distribution of fine bronchi, several areas of widened alveolar septa and dense cells (shown in the red box) still clearly demarcated from the surrounding lung tissue, without an envelope. (B) x40 HE shows widened alveolar septa, lesion cells growing along the alveolar septa and an open air cavity. (C) HE x100 lesion cells partially growing around the blood vessels. (D) HE x200 shows that the lesion cells are round or ovoid, with relatively normal morphology, abundant cytoplasm, unclear cell demarcation, light stained nuclei with delicate chromatin and without atypia,.
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The nucleus was light stained, and delicate chromatin was evenly distributed ( Figure 3 ).
Immunohistochemical results of MPMNs. (A) x200 The cells were nuclear positive for PR; (B) x200 The cells were cytoplasmic positive for EMA; (C) x200 The cells were cytoplasmic positive for CD56; (D) x200 The cells were both nuclear and cytoplasmic positive for vimentin; (E) x200 Normal type II alveolar epithelial cells were positive and meningeal epithelial-like cells were negative for TTF-1; (F) x200 The number of Ki-67 positive cells was <1%.
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