Abstract

A case of endometriosis presenting as a mass in the groin of a pregnant woman is described. The mass increased in size during the pregnancy and the radiological features were suspicious of malignancy. Histological examination showed atrophic glands set in an abundant stroma. This was not typical of normal endometrial stroma but had a pronounced myxoid appearance with areas of decidualisation. The atypical site of the endometriosis together with the unusual stromal changes resulted in diagnostic confusion. Although stromal decidualisation is well recognised in endometriosis in pregnancy, pronounced myxoid change appears unusual. The myxoid change in this case may be a degenerative phenomenon related to pregnancy.