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Lung tumor

Benign tumors


Reviewer: Deepali Jain, M.D. (see Reviewers page)
Revised: 3 November 2014, last major update September 2012
Copyright: (c) 2003-2014, PathologyOutlines.com, Inc.


● Rare progressive lung disease in women due to mutations in tuberous sclerosis genes, resulting in activation of the mTOR complex 1 signaling network (J Clin Invest 2012;122:3807)
● Also called lymphangiomyomatosis
● May be due to metastases or migration of smooth muscle progenitor cells from uterus, since uterine involvement is a common manifestation (Am J Surg Pathol 2011;35:1776)
● Have severe impairment of diffusion with air trapping and expanding lung volumes (dyspnea with pneumothorax or emphysema, without a smoking history)

Clinical features

● Almost always women, usually white and of reproductive age
● Rare cases in men or postmenopausal women on hormone replacement
● Associated with tuberous sclerosis, renal angiomyolipomas
● May diffusely involve both lungs; may also involve mediastinal or periaortic lymph nodes
● Disease is progressive, prognosis poor, death due to respiratory failure or cor pulmonale
● Disease worsened by pregnancy or menstruation, improved post-menopause
● Complications: respiratory insufficiency and death, spontaneous pneumothorax, chylous pleural effusion


● Oophorectomy, hormone manipulation (progesterone or antiestrogens), lung transplantation (but may recur in lung allografts, Hum Pathol 2003;34:95)

Gross description

● Emphysematous-like changes to widespread cystic spaces separated by thick, gray-white septa

Micro description

● Cystic air spaces and patchy disordered nodular proliferation of bland smooth muscle around airways, lymphatics, blood vessels
● Proliferating smooth muscle cells expand lung parenchyma
● Resembles renal angiomyolipoma in that smooth muscle appears to spin off muscle coats of these structures, extending towards adjacent alveoli
● Muscle cells have optically clear cytoplasm, intracytoplasmic glycogen
● Hemosiderin pigment is common

Gross images

Various images

Micro images

Various images

Positive stains

● HMB45, ER, PR, beta catenin (Am J Clin Pathol 2011;135:776)

Differential diagnosis

Benign metastasizing leiomyoma: well circumscribed, single or multiple nodules of smooth muscle, composed of elongated cells with abundant eosinophilic cytoplasm, oval nuclei, inconspicuous nucleolioften focal, HMB45-
Idiopathic pulmonary hemosiderosis: hemosiderin laden macrophages in alveolar lumina, shedding and hyperplasia of alveolar epithelial cells and marked alveolar capillary congestion; HMB45-
● Metastatic endometrial sarcoma
Micronodular pneumocyte hyperplasia

End of Lung tumor > Benign tumors > Lymphangioleiomyomatosis

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