Stanford School of Medicine

Surgical Pathology Criteria

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  • Pulmonary disease of women of reproductive age characterized by growth of nodules of modified smooth muscle cells and lymphatics

Diagnostic Criteria

  • Clinical
    • May be sporadic or associated with tuberous sclerosis complex (TSC)
    • Virtually restricted to women of child bearing age
      • Rare males and children affected in TSC kindreds
      • Present in 30% of females with TSC
    • Presents with dyspnea, pneumothorax, chylous effusions
    • May have associated renal angiomyolipoma (>50%) and meningioma
    • Prolonged course but poor prognosis unless transplanted
  • HRCT
    • Cysts scattered diffusely throughout the lung
      • Most are 2-5 mm, occasionally up to 30 mm
  • Histopathology
    • Diagnosis can be made without tissue confirmation if clinical history and radiology are appropriate
    • Multifocal nodules of modified smooth muscle cells
      • Slightly increased cytoplasm
        • May have "shredded" appearance (not uniform and dense)
      • Smooth muscle actin and desmin strong positive
      • HMB45 positive but frequently focal or faint
      • May involve interstitium, walls of bronchi and arteries
    • Lymph vascular proliferation
      • May be slit-like within muscle nodules or may be dilated
    • Cysts form from obstructed airways
      • Thin walled except where involved by nodules of modified muscle cells
    • May be seen in transplanted lung but generally not significant clinically
    • LAM is a neoplasm in spite of its bland appearance
      • Mutations in TSC1 or 2 in familial cases
      • Mutations in TSC2 in sporadic cases

Gerald J Berry MD
Robert V Rouse MD
Department of Pathology
Stanford University School of Medicine
Stanford CA 94305-5342

Original posting/updates: 11/20/10

Differential Diagnosis

Lymphangioleiomyomatosis Metastatic Leiomyosarcoma
Cytologically bland Cytologically atypical
Innumerable small clusters and nodules Usually fewer, larger nodules
Virtually always forms cysts Does not form cysts
HMB45 positive HMB45 negative


Lymphangioleiomyomatosis Metastatic Melanoma
Virtually always forms cysts Does not form cysts
Virtually always forms cysts Does not form cysts
Smooth muscle actin and desmin positive Smooth muscle actin and desmin negative
Both are HMB45 positive


Lymphangioleiomyomatosis Emphysema
Discrete small cysts set in a background of normal lung Irregular spaces blending with existing airways
Nodules of smooth muscle in walls of cysts No smooth muscle nodules
HMB45 positive Nothing in normal or emphysematous lung is HMB45 positive

Classification / Lists

Idiopathic Interstitial Lung Diseases

Other Diffuse Parenchymal Lung Diseases



  • Seyama K, Kumasaka T, Kurihara M, Mitani K, Sato T. Lymphangioleiomyomatosis: a disease involving the lymphatic system. Lymphat Res Biol. 2010 Mar;8(1):21-31.
  • Johnson SR, Cordier JF, Lazor R, Cottin V, Costabel U, Harari S, Reynaud-Gaubert M, Boehler A, Brauner M, Popper H, Bonetti F, Kingswood C; Review Panel of the ERS LAM Task Force. European Respiratory Society guidelines for the diagnosis and management of lymphangioleiomyomatosis. Eur Respir J. 2010 Jan;35(1):14-26.
  • Matsui K, Beasley MB, Nelson WK, Barnes PM, Bechtle J, Falk R, Ferrans VJ, Moss J, Travis WD. Prognostic significance of pulmonary lymphangioleiomyomatosis histologic score. Am J Surg Pathol. 2001 Apr;25(4):479-84.
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  • Kumasaka T, Seyama K, Mitani K, Sato T, Souma S, Kondo T, Hayashi S, Minami M, Uekusa T, Fukuchi Y, Suda K. Lymphangiogenesis in lymphangioleiomyomatosis: its implication in the progression of lymphangioleiomyomatosis. Am J Surg Pathol. 2004 Aug;28(8):1007-16.
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