Extrapulmonary lymphangioleiomyomatosis (LAM): clinicopathologic features in 22 cases

Hum Pathol. 2000 Oct;31(10):1242-8. doi: 10.1053/hupa.2000.18500.


We describe the lesions of extrapulmonary lymphangioleiomyomatosis (LAM) affecting the lymph nodes of the mediastinum and retroperitoneum in 22 women (mean age +/- SD, 42.4+/-10.5 years). In most of these patients, the diagnosis of extrapulmonary LAM preceded that of pulmonary LAM, usually by 1 to 2 years. Eleven patients had distinct symptoms, including chylous pleural effusion and/or ascites, abdominal pain, and palpable abdominal masses. In the other 11 patients, the masses caused no symptoms. Well-circumscribed, encapsulated masses, measuring up to 20 cm in size, occurred in the mediastinum in 2 patients, the upper retroperitoneum in 15, extensive areas of the retroperitoneum in 2, and the pelvis in 3. The masses exceeding 3 cm in diameter contained large, multiple cysts filled with yellow-tan chylous fluid. Histologically, the masses were characterized by a proliferation of smooth muscle cells (LAM cells) arranged in fascicular, trabecular, and papillary patterns, which were associated with slit-like vascular channels. The LAM cells varied from small, spindle-shaped cells to large epithelioid cells. Immunohistochemical studies showed a strong reactivity of most LAM cells for alpha-smooth muscle actin and smooth muscle myosin heavy chain and a weak to moderate reactivity of a lesser number of cells for desmin and nonmuscle myosin heavy chain II-B. A reaction for HMB-45 and estrogen and progesterone receptors was observed mainly in epithelioid LAM cells. These patterns of reactivity are similar to those observed in pulmonary LAM. However, the chylous cysts are not a feature of pulmonary LAM and are thought to result from obstruction of lymphatics.

Publication types

  • Review

MeSH terms

  • Actins / analysis
  • Adult
  • Aged
  • Antigens, Neoplasm / analysis
  • Antigens, Surface / analysis
  • Female
  • Humans
  • Lymphangioleiomyomatosis / pathology*
  • Melanoma-Specific Antigens
  • Middle Aged
  • Myosin Heavy Chains / analysis
  • Neoplasm Proteins / analysis


  • Actins
  • Antigens, Neoplasm
  • Antigens, Surface
  • Melanoma-Specific Antigens
  • Neoplasm Proteins
  • Myosin Heavy Chains