A ventilation perfusion (V/Q) scan was performed in a 47-year-old woman in whom, following a total hysterectomy, worsening hypoxia and dyspnea developed.The ventilation image showed inhomogeneous distribution in the equilibrium phase (figure 1A), with diffuse retention in the washout phase (figure 1B). Matching moderate patchy perfusion was noted, most prominently at both bases (figure 2).
CASE SUMMARY:
A ventilation perfusion (V/Q) scan was performed in a
47-year-old woman in whom, following a total hysterectomy,
worsening hypoxia and dyspnea developed.The ventilation image
showed inhomogeneous distribution in the equilibrium phase (figure
1A), with diffuse retention in the washout phase (figure 1B).
Matching moderate patchy perfusion was noted, most prominently at
both bases (figure 2). The correlating chest x-ray demonstrated a
bilateral, moderate to severe interstitial reticular pattern, with
numerous small cysts giving a honeycomb appearance that was
prominent in both the mid and lower lung zones (figure 3). Computed
tomography (CT) of the upper, mid, and lower lung zones showed
diffuse and extensive, predominantly small to medium sized cystic
changes with associated prominent lung markings (figure 4). The V/Q
scan was interpreted as a low probability for pulmonary
thromboembolism. The patient was treated for mild pulmonary edema
due to fluid overload and discharged without complications.
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.
References
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 Iymph-angioleiomyomatosis. 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.
Prepared by Jyotsna Rao, MD; Stephen J. Pomeranz, MD, Parshan S.
Ramsingh, MD; and José R. Barreras, Department of Nuclear Medicine
and Metabolic Imaging, The Christ Hospital, Cincinnati, OH.