Lymphangioleiomyomatosis

Clinical History

The patient presented with progressive exertional dyspnoea over more than a year. There was no significant medical history.

Imaging Findings

The patient presented with progressive exertional dyspnoea over more than a year. There was no significant medical history. Cardiac investigation was negative. Conventional radiographs and CT of the chest were performed. Based on the presence of a chylothorax and numerous thin-walled cysts, a diagnosis of pulmonary lymphangioleiomyomatosis (LAM) was suggested. Diagnosis was confirmed on open lung biopsy. Two years after the initial diagnosis, the patient underwent unilateral lung transplantation.

Discussion

Pulmonary lymphangioleiomyomatosis (LAM) is a rare disorder and occurs almost exclusively in women of childbearing age. Abnormal proliferation of immature smooth muscle cells around the airways, blood vessels and lymphatic vessels, explains the clinical manifestations. Lymphatic obstruction leads to the formation of a chylothorax. Obstruction of the pulmonary vessels causes venular congestion and disruption, resulting in haemoptysis. Airflow obstruction, secondary to the compressed airways, leads to alveolar disruption, which is responsible for the formation of the thin-walled cysts. CT can easily detect these cysts within the lungs. The cysts appearing in LAM are quite characteristic in the correct clinical setting and can be differentiated from other similar pathologies, such as Langerhans cell histiocytosis, Wegener granulomatosis, septic pulmonary emboli, pneumocystic carinii pneumonia, usual interstitial pneumonia, lymphocytic interstitial pneumonia, etc. Cysts in LAM are numerous, thin walled, varying in size from a few millimeters to 5cm and with a distribution in all lung zones. In conjunction with these cysts, characteristic abdominal findings, are useful in establishing the diagnosis. The most common abdominal findings include renal angiomyolipoma (54%), enlarged abdominal lymph nodes (39%), and lymphangiomyoma (16%).

LAM can occur as a rare sporadic disease or as a complication of tuberous sclerosis (TSC). The concomitant finding of renal angiomyolipomatas (the hallmark of TSC) in LAM, supports the hypothesis that both entities are linked; LAM is actually considered as a form fruste of TSC. TSC, however, occurs in patients of either sex. Diagnosis of LAM is made on open lung biopsy, as there is still debate whether the diagnosis may be ruled out on the basis of a normal CT scan. LAM continues to frustrate clinicians attempting to treat it. Great importance was given to hormonal therapy as the entity occurs almost exclusively in women, but this did not prove to be effective. Although disease-related complications are frequent, lung transplantation can be a valuable therapy for patients with end-stage LAM.

Differential Diagnosis List

Final Diagnosis

Pulmonary lymphangioleiomyomatosis

URL:	https://eurorad.org/case/1673
DOI:	10.1594/EURORAD/CASE.1673
ISSN:	1563-4086