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Case 307 - Discussion

Uploaded: 2009-08-15, Updated: 2009-08-15

Lymphangioleiomyomatosis (LAM)

  • Young women of childbearing age, more common in white female.

  • Occurs in women with tuberous sclerosis, but most LAM patients do not have TS.

  • Renal angiomyolipomas occur in ~60% of LAM cases.

  • Radiographic: reticular pattern 80% of cases, pneumothorax 30-40%, unilateral or bilateral effusion 10-20%. Later hyperinflation. HRCT, numerous thin-walled cysts, 0.2-2.0 cm in diameter, diffusely throughout the lungs.

  • Gross: diffuse, bilateral cystic changes throughout. Lungs are enlarged. Most cysts 0.5-2.0 cm, some may be up to 10 cm.

  • Micro: cystic changes and LAM cell infiltration. LAM cells are typically in small clusters or nests at the edge of the cysts an along pulmonary lymphatics. In advanced cases, LAM cells can become so prominent that it is difficult to identify the normal lung architecture. LAM cells infiltrate the vascular walls and distal airways, leading to vascular destruction and microscopic foci of hemosiderosis. Typical LAM cells are round, oval or spindle-shaped. They grow in a haphazard arrangement.  They have a moderate amount of eosinophilic cytoplasm. Nuclei have fine chromatin or vesicular chromatin.

  • IPX: SMA+, desmin+, vimentin+, HMB45+.

  • DDX:

    • Hyperplasia of interstitial smooth muscle in honeycomb fibrosis

    • Lymphangiomatosis: infants or young children of both genders, proliferation of endothelial-lined spaces along lymphatic routes.

    • Lymphagioma: extremely rare, solid coin lesion.

  • Prognosis: 8-10 years of median survival.