Lymphangioleiomyomatosis

Fig. 23.5 Cystic metastasis in a 20-year-old man with osteogenic sarcoma in right thigh. (a, b) Lung window images of CT scan (5.0-mm section thickness) obtained at levels of left inferior pulmonary vein (a) and basal segmental bronchi (b), respectively, show cystic lung lesions (arrows). (c) Low-magnification (×4) photomicrograph of surgical

biopsy specimen depicts a unilocular cyst with thin wall (arrows) which is composed of metastatic tumor cells. (d) High-magnification (×100) photomicrograph discloses cyst wall composed of spindle-shaped pleomorphic tumor cells permeating bronchiolar wall

Lymphangioleiomyomatosis

Pathology and Pathogenesis

The essential pathologic feature is a proliferation of unusual smooth muscle cells that involves all parts of the lungs (Fig. 23.3). They are generally plump and spindle-shaped with pale eosinophilic cytoplasm but the cytoplasm may be clear and the cells are polygonal in outline so that they appear epithelioid. The alveolar walls are infiltrated by the

unusual smooth muscle cells and consequently thickened, often in nodular fashion. Narrow lymphatic channels are often evident within these cell collections. Consequent breakdown of the alveolar walls leads to focal cystic change, which ultimately culminates in gross “honeycombing” throughout the lungs. Airway collapse consequent upon this cystic change is the principal mechanism contributing to airflow limitation. Rupture of the cysts explains the frequent pneumothoraces which are one of the distinctive complications of this disease [21].

Fig. 23.6 Cystic metastasis in an 82-year-old man with angiosarcoma in his scalp. (a, b) Lung window images of CT scan (5.0-mm section thickness) obtained at levels of aortic arch (a) and arising portion of right middle lobar bronchus (b), respectively, show cystic lung lesions (arrows) in both lungs. A pigtail catheter (open arrow) was inserted in right pleural space in order to evacuate pneumothorax caused by rup-

ture of cystic lung lesions. (c) Coronal reformatted image (2.0-mm section thickness) also demonstrates multiple cystic lung lesions. Also note pneumothorax (open arrow) in right apex. (d) Enhanced CT (5.0- mm section thickness) scan of brain depicts a band-like highly enhancing soft tissue tumor (arrows) in left scalp, anteriorly, which turned out to be an angiosarcoma

Patients with LAM usually develop progressive dyspnea and recurrent pneumothorax, chylous effusions, and occasional hemoptysis [22]. Extrapulmonary lymphadenopathy and cystic masses of the axial lymphatics can be found in abdomen or pelvis. In patients with tuberous sclerosis, LAM is often associated with angiomyolipoma in the kidneys and liver. Meningioma is also frequently found.

Characteristic HRCT findings of LAM are diffuse thinwalled cysts surrounded by normal lung without regional sparing [18, 23] (Fig. 23.3). Cysts are usually 2–5 mm but can be as large as 25–30 mm. Cysts are typically round or ovoid, but they may become polygonal with severe parenchymal involvement. Other findings include thickening of interlobular septa, small centrilobular nodules, and focal areas of ground-glass opacity (GGO).