Lymphangioleiomyomatosis (LAM) has always fascinated me since I saw a case as a young trainee pathologist. Was an apparently benign tumour of smooth muscle in the uterus (as it was in that case) really ‘metastasising’ in lymphovascular channels? Our knowledge of this condition has moved on since then and we now know it to be often found in patients with pulmonary lymphangiomyomatosis, the tuberous sclerosis complex and other vascular neoplasms. Rabban et al. have published an excellent clinicopathological study in this month’s American Journal of Surgical Pathology which looks at clinically occult LAM in pelvic lymph nodes removed for tumours of the uterus, ovary, cervical or bladder. They found 26 cases – none had pulmonary LAM and only 2 had tuberose sclerosis complex. This shows that clinically-occult LAM is still largely a condition which doesn’t have any particular associations with other disease complexes and its pathogenesis is still obscure.