Fig. 2

Pathological findings in patients with lymphangioleiomyomatosis (LAM) and comorbid connective tissue diseases (Cases 1–4). a-d Photomicrographs of surgical lung biopsy (SLB) in Patient 1. a, b Haematoxylin and eosin (H&E) staining was observed at a magnification of × 10 and × 40, respectively. Clumps of spindle cells with eosinophilic cytoplasm were noted in the lung interstitium and regarded as LAM cell nests (central right, lower left) (b). The lung interstitium around the small blood vessels exhibited a small lymphoid follicle (lymphoid cell aggregates) (arrow). c, d Alpha-smooth muscle actin (αSMA) and human melanoma black-45 (HMB45) immunostaining results were positive in LAM cell nests (magnification, × 40). e-h Photomicrographs of SLB in Patient 2. (e) H&E staining revealed lymphoid cell aggregate (arrow) and focal fibrotic lesions in the wall of a cystic lesion (7 × 14 mm) as well as proliferation of LAM cells (magnification, × 10). f, H&E staining revealed another cystic lesion and alpha-MA-positive LAM cell nest in the wall (alpha-SMA, not shown) (magnification, × 10). g, h A LAM cell nest testing positive for αSMA and HMB45 antibodies (magnification, × 40). i, j Photomicrographs of SLB in Patient 3. i, H&E staining showing infiltration of lymphoid cells into the wall of a membranous bronchiole (arrow) and two cystic lesions measuring 1.5 × 1 mm and 1.7 × 1.2 mm due to LAM (magnification, × 2). j Positive HMB45 staining was observed in a LAM cell nest in the lower right area of i (magnification, × 40). k, l Photomicrographs of transbronchial lung biopsy in Patient 4. (K) H&E staining revealed a LAM cell population (central area) with eosinophilic cytoplasm, which tested positive for oestrogen receptor (ER) and progesterone receptor (PgR), in the wall of a D2–40 positive-cell lined lymphatic vessel measuring 200 μm in diameter (central lower area) (magnification, × 10) (ER, PgR, and D2–40, not shown). l Another LAM cell nest testing positive for HMB45 following transbronchial biopsy (magnification, × 40)