Sporadic lymphangioleiomyomatosis and tuberous sclerosis complex with lymphangioleiomyomatosis: comparison of CT features

Abstract

Purpose: To retrospectively compare the frequencies of computed tomographic (CT) findings in patients with lymphangioleiomyomatosis (LAM) and patients with tuberous sclerosis complex (TSC) and LAM.

Materials and methods: Institutional review board approval and informed consent were obtained for the HIPAA-compliant study. In 256 patients with LAM (mean age, 44 years) and 67 patients with TSC/LAM (mean age, 40 years), CT scans of the chest, abdomen, and pelvis were reviewed by a single radiologist. The fraction of lung involvement with cysts was estimated from high-spatial-resolution CT scans. Other findings assessed included noncalcified pulmonary nodules, pleural effusion, thoracic duct dilatation, hepatic and renal angiomyolipomas (AMLs), lymphangioleiomyoma (LALM), ascites, nephrectomy, and renal embolization. Confidence intervals and hypothesis tests of differences in frequencies, comparison of age quartiles, RIDIT analysis, analysis of variance, and correlation coefficients were used in the statistical analysis.

Results: Patients with LAM had more extensive lung involvement (RIDIT score, 0.36) and higher frequency of LALM (29% vs 9%, P<.001), thoracic duct dilatation (4% vs 0, P=.3), pleural effusion (12% vs 6%, P=.2), or ascites (10% vs 6%, P=.3). Patients with TSC/LAM had higher frequency of noncalcified pulmonary nodules (12% vs 1%, P<.01), hepatic (33% vs 2%, P<.001) and renal (93% vs 32%, P<.001) AMLs, nephrectomy (25% vs 7%, P<.001), or renal artery embolization (9% vs 2%, P<.05).

Conclusion: The extent of lung disease is greater in LAM than TSC/LAM. Hepatic and renal AMLs and noncalcified lung nodules are more common in TSC/LAM, while lymphatic involvement-thoracic duct dilatation, chylous pleural effusion, ascites, and LALM-is more common in LAM.

Figure 1

Transverse prone nonenhanced high-spatial-resolution 1-mm-thick CT section in a 56-year-old woman with LAM shows severe involvement of the lungs. Note almost complete replacement of lung tissue by cysts.

Figure 2

Graph shows that mean lung grades for patients with LAM are consistently greater than those for patients with TSC/LA Macross all four age quartiles.

Figure 3

Transverse 5-mm-thick contrast-enhanced CT section through upper lungs in a 55-year-old woman with TSC/LAM. Multiple lung nodules (arrow-heads) consistent with multifocal micronodular pneumocyte hyperplasia and few lung cysts (arrow) indicate minimal lung involvement with LAM.

Figure 4

Schematics show overall and conditional probabilities of renal AML, hepatic AML, and LALM in patients with (a) LAM and (b) TSC/LAM. Numbers in boxes are overall probabilities of findings in each group. Number associated with each arrow is conditional probability of the finding to which the arrow points, given presence of the finding from which the arrow originates. For example, in patients with LAM, 32% had a renal abnormality, and of those 17% had LALM; 29% had LALM, and of those 19% had a renal abnormality. Renal and hepatic AMLs were more common in patients with TSC/LAM than in patients with LAM. LALM was more common in patients with LAM.

Figure 5

Transverse 5-mm-thick contrast-enhanced CT section through midabdomen in a 46-year-old woman with TSC/LAM. Note fatty hepatic lesion (arrowhead) and too-numerous-to-count bilateral renal fatty lesions.

Figure 6

Transverse 5-mm-thick contrast-enhanced CT section through lower abdomen in a 25-year-old woman with LAM and large multiseptated complex retroperitoneal mass consistent with LALM. Note anterior displacement of aorta (A) and IVC (V) by the mass (*).

Figure 7

Graph shows that frequencies of renal AML and/or nephrectomy were consistently much higher in TSC/LAM group than in LAM group across all age quartiles.

Figure 8

Graph shows that mean total renal score (total number of AMLs and nephrectomies in both kidneys) in patients with renal abnormalities was consistently much higher in TSC/LAM group than in LAM group across all age quartiles.

Figure 9

Scatterplots of age versus total renal score for patients with (a) LAM and (b) TSC/LAM. Comparison of distribution of data points demonstrates tendency of total renal scores of patients with LAM to be lower than those of patients with TSC/LAM across age range of patients examined.

Figure 10

Graph shows that for each grade (extent of lung disease), probability of renal disease is much higher in patients with TSC/LAM than in patients with LAM and is relatively constant across grades, without evidence of positive trend or correlation between extent of lung cysts and probability of renal disease.

Figure 11

Graph shows that for each grade (extent of lung disease), mean total renal score in patients with renal abnormalities is much higher in patients with TSC/LAM than in patients with LAM, without evidence of positive trend or correlation between lung and renal disease severity.

Figure 12

Cumulative probability distribution of patients’ ages. Curves are shifted about 4 years relative to one another but are similar in shape, indicating that LAM patients were, on average, about 4 years older than TSC/LAM patients. Age distribution plots of patients in the two groups were of similar shape and/or spread.