S-LAM (Sporadic Pulmonary Lymphangioleiomyomatosis): Supporting the Theory of Pelvic Origin

Abstract

INTRODUCTION: S-LAM is an uncommon disorder with average annual incidence of 4 cases per million, which most commonly presents in women of childbearing age suggesting estrogen is important in the pathophysiology. S-LAM is classified as a low grade malignancy by the WHO, which most typically arises in the pulmonary parenchyma. Our case report highlights another potential primary site from which this malignancy may arise - the female genital tract. This case highlights the insidious and progressive nature of this tumor and why physicians must cast a broad differential diagnosis in those presenting with reoccurring abdominal pain. Based on the recently developed European Respiratory Guidelines, a confident clinical diagnosis of LAM can be made in patients who present with a compatible HRCT pattern and chylous effusion. CASE PRESENTATION: A Middle aged who continued to suffer for years from recurrent abdominal pain and chylous ascites. Extensive workup was negative for lymphoma and pelvic malignancy. Five years later the patient developed right sided chylous effusion. CT chest revealed multiple cystic lung lesions typical of lymphangiomyeilomatosis. The patient was treated with VATS, mechanical pleurodesis and bleb stapling. One year later she developed a second attack of right sided chylothorax for which she had a second VATS with talc pleurodesis and thoracic duct ligation. Afterwards the patient was started on sirolimus which resulted in marked improvement in her symptoms. Unfortunately, the patient had to discontinue sirolimus after 10 months due to severe recurrent muco-stomatitis. Three months after stopping the sirolimus the patient developed a third attack of chylothorax this time on the left side for which she had her third VATS for evacuation of chylothorax followed by mechanical pleurodesis and talc application to pleural surfaces DISCUSSION: The source of LAM cells has remained unclear, akin to a cancer of unknown primary. LAM cells have been recently classified as perivascular epithelioid cell tumors, or PEComas. PEComas are most commonly found in the uterus and peritoneum. A recent study found a very high prevalence of uterine PEComa lesions in patients with S-LAM fueling speculation that uterus may be the <<primary tumor>> source of LAM cells in many cases. CONCLUSIONS: S-LAM is a rare disease that usually presents with pulmonary symptoms. The primary pathological abnormality is thought to be due to proliferation of atypical smooth muscle and epithelioid cells around bronchovascular structures under the effect of estrogen. Recently, there has been an increased number of case reports manifesting initially with pelvic symptoms. This raises the suspicion that the tumor originates from the pelvis and then slowly ascends the lymphatic system to reach and inhabits the lungs