Extrapulmonary lymphangioleiomyomatosis (LAM): clinicopathologic features in 22 cases

Area of Science:

• Oncology
• Pathology
• Radiology

Background:

• Lymphangioleiomyomatosis (LAM) is a rare neoplastic proliferation of smooth muscle cells.
• Extrapulmonary LAM involvement of lymph nodes is less common than pulmonary LAM.
• Understanding extrapulmonary LAM lesions is crucial for diagnosis and management.

Purpose of the Study:

• To describe the histopathological and imaging features of extrapulmonary LAM in lymph nodes.
• To compare extrapulmonary LAM lymph node lesions with pulmonary LAM.
• To investigate the immunohistochemical profile of LAM cells in lymph node masses.

Main Methods:

• Retrospective analysis of 22 women with extrapulmonary LAM affecting mediastinal and retroperitoneal lymph nodes.
• Review of imaging findings (size, location, cystic changes).
• Histopathological examination including immunohistochemistry (alpha-smooth muscle actin, smooth muscle myosin heavy chain, desmin, HMB-45, ER, PR).

Main Results:

• Diagnoses of extrapulmonary LAM preceded pulmonary LAM by 1-2 years in most patients.
• Masses varied in size (up to 20 cm) and location (mediastinum, retroperitoneum, pelvis).
• Cysts filled with chylous fluid were present in masses >3 cm, a feature not seen in pulmonary LAM.
• LAM cells showed characteristic smooth muscle markers; HMB-45 and hormone receptor positivity noted in epithelioid cells.
• Immunohistochemical findings were similar to pulmonary LAM.

Conclusions:

• Extrapulmonary LAM in lymph nodes presents as well-circumscribed masses, often with chylous cysts.
• These lesions can precede pulmonary LAM diagnosis and may cause symptoms like effusions or abdominal masses.
• Immunohistochemical profiles are consistent with LAM, supporting a common neoplastic origin with pulmonary LAM.