Applied Radiology

Diagnosis

The patient was diagnosed with lymphangioleiomyomatosis (LAM) eight years ago, proven by biopsy.

Discussion

LAM, a rare disease seen in women of childbearing age, was first described 50 years ago. Its true incidence is not known.¹ LAM affects women exclusively, except in some cases of an incomplete form of tuberous sclerosis in men. Incidence of LAM tends to increase in pregnancy, during use of oral contraceptives, and during menses.² Clinical findings in LAM include chest pain, hemoptysis, dyspnea, exertional dyspnea, chylothorax, and pneumothorax (the latter being the most common, presenting with resting dyspnea).^3,4 Diagnosis can be made by transbronchial biopsy or tissue obtained by thoracoscopy or thoracotomy. Laboratory findings include elevated angiotensin converting enzyme and eosinophilia.¹ Presentation can be heterogeneous, and the initial clinical diagnosis given to patients may be chronic obstructive pulmonary disease, asthma, bronchitis, interstitial lung disease of unknown cause, idiopathic hemosiderosis, sarcoidosis, and paraquat lung.^4,5 Ventilation/perfusion scans show a typical interstitial disease pattern with bilateral patchy diminished activity on both phases and retention noted in the abnormal areas on the ventilation phase. Chest CT may show changes earlier than on chest x-ray and may be more accurate in defining cysts and the extent of disease. CT is also more sensitive than pulmonary function tests in the early stages of LAM.⁶ One typical finding on chest CT is cystic air spaces of various sizes surrounded by relatively normal lung parenchyma. The cysts involve the lungs diffusely, with cysts ranging in size from 0.5 cm in mild disease to 1 cm when there is greater than 80% involvement. The presence of many thin walled cystic air spaces throughout both the lungs in a young woman is pathognomonic of LAM in the appropriate clinical setting.⁷ The differential diagnosis for the radiological patterns of the disorder includes pneumoconioses, fungal, viral, and bacterial infections, autoimmune diseases, radiation injury, and drug reaction (as with antiobiotics and antineoplastic drugs). Histology reveals smooth muscle proliferation around the blood vessels and lymphatic vessels. Compression of the airway results in obstruction and alveolar disruption, leading to distal cystic changes. Obstruction of pulmonary vessels causes venous congestion and disruption; lymphatic obstruction leads to chylothorax.⁴ The histological appearance of LAM is indistinguishable from that of tuberous sclerosis, which rarely involves the lungs; however, when there is lung involvement in tuberous sclerosis, the clinical and pathological features are identical to those of LAM. Pulmonary function tests show decreased forced expiratory volume (FEV), forced vital capacity (FEV1/FVC) and diffusion capacity (Dlco), and increased total lung capacity (TLC) and residual lung volumes.¹ Once LAM is diagnosed, treatment should begin immediately. As hormonal dependency seems a likely cause, based on the age group of the patients and progesterone levels, bilateral oophorectomy and tamoxifen administration have been used in an attempt to reduce or counteract estrogen, although the latter seems to worsen the disease.^1,8,9 Patients with chylous ascites or effusions seem to respond to progesterone therapy, and the presence of chyle may indicate a reversible element.⁴ Symptomatic treatment of pneumothorax and chylothorax can be done using pleurodesis, although hormonal manipulation should be attempted first in the presence of chylothorax. For cases of progression despite hormonal treatment, lung transplantation has been attempted. Experimental forms of treatment include use of luteinizing hormone-releasing hormone (LHRH) analogues, danatrol, and ketoconazole.¹ Though considered universally fatal, survival up to 20 years after diagnosis has been described.¹ Though rare, LAM should be a consideration when a complex cystic interstitial disease pattern is seen in women, especially those in the childbearing age group.

1. Viskum K: Pulmonary Iymphangioleiomyomatosis. Monaldi Arc Chest Dis 48(3):233-236, 1993.
2. Urban T, Kuttenn F, Gompel A, et al: Pulmonary Iymphangioleiomyomatosis: Follow-up and long-term outcome with antiestrogen therapy; a report of eight cases. Chest 102:4726, 1992.
3. Bennett JC, Plum F: Respiratory Diseases. In: Cecil's Textbook of Medicine, ed 19. Philadelphia, WB Saunders, 1992.
4. Taylor JR, Ryu J, Colby TV, Raffin TA: Lymphangioleiomyomatosis: Clinical course in 32 patients. N Engl J Med 323:1254-1260, 1990.
5. Chuang ML, Tsai YH, Pang LC: Early chylo-pneumothorax in a patient with pulmonary Iymphangioleiomyomatosis. J Formos Med Assoc 92(3):278-282, 1993.
6. Alberle DR, Hansell DM, Brown K, Tashkin DP: Lymphangioleiomyomatosis: CT, chest radiography, and functional correlations. Radiology 176:381-387, 1990.
7. Muller NI, Chiles C, Kullnig P:Pulmonary Iymphangioleiomyomatosis; correlation of CT with radiographic and functional findings. Radiology 175:335-339, 1990.
8. Anker N, Francis D, Viskum K: Two case of Iymphangioleiomyomatosis treated by hormonal manipulation. Ugeskrift for Laeger 155(30):2354-2356, 1993.
9. Klein M, Kreriger O, Ruckser R, et al:Treatment of lymphangioleiomyomatosis by ovariectomy, interferon alpha 2b and tamoxifen-A case report. Arch Gynecol Obstet (abstr) 252(2):99-102, 1992.