Unusual lymphangioleiomyomatosis presenting as a pure perivascular growth pattern

Lymphangioleiomyomatosis (LAM) is a rare disease mainly affecting women of child-bearing age that primarily involves lung parenchyma smooth muscles with resulting cystic changes. This disease can present symptomatically as shortness of breath or as a recurrent pneumothorax. Rare instances of extrapulmonary manifestations involving the kidneys and other visceral organs have been reported. Herein, we describe an unusual case of LAM in a patient with a retroperitoneal mass showing pure perivascular growth pattern. We report a case of a 41-year-old female who presented with abdominal pain and was found to have a left para-aortic mass. This was at the aortic bifurcation and concerning for a paraganglioma; however, laboratory analysis excluded a functional mass. The patient was lost to follow-up due to complications from the COVID-19 pandemic and established care 4 years later, at which time biopsy revealed the diagnosis of LAM. She ultimately underwent surgical resection. This is a unique presentation of non-pulmonary, para-aortic LAM. This case reviews the relevant literature and presents a methodical histologic work up of this unusual mass.