Lymphangioleiomyoma

Lymphangioleiomyomas are proliferations of smooth muscle cells in lymphatic vessels, leading to obstruction and dilation that results in cystic collections of chyle. They can be seen in about 15% of patients with lymphangioleiomyomatosis (LAM).

These dilated retroperitoneal lymphatic vessels can present as thick- or thin-walled masses with or without central low attenuation (~5 HU to 25 HU). Rupture may result in chylous ascites (-10 HU to 20 HU).

Isolated retroperitonel involvement can cause a diagnostic dilemma. Differential considerations in these cases include:

• Enlarged lymph nodes: Enlarged nodes may be seen in patients with LAM, and some of these lymph nodes have central areas of low attenuation (−70 HU to 50 HU).
• Cystic lymphangioma:
• Neoplasm: Lymphoma or metastases. Primary cystic retroperitoneal tumors (liposarcoma, leiomyosarcoma, and fibrosarcoma) with cystic degeneration will usually have solid components.
• Fluid collections: Old hematoma, abscess, urinoma, and lymphoceles.

Thanks to Dr. Mark Bankoff for the case.

References

Avila NA, Kelly JA, Chu SC, Dwyer AJ, Moss J. Lymphangioleiomyomatosis: abdominopelvic CT and US findings. Radiology. 2000 Jul;216(1):147-53.