Investigations on uterine fatty lesions

The aim of the study was to determine the occurrence of UFLs and the dynamics of their development, as well as to evaluate the histopathology and relationship with regressive stromal changes. 3750 uterine specimens were reviewed during the period between 1984 and 2003. In the examined series of 3750 uteruses removed due to tumors or prolapse, 50 cases with four types of changes were chosen: adipocytic metaplasia of primary uterine leiomyomas (70% of cases), adipocytic metaplasia of interlobular stroma of primary uterine tumors (16%), adipocytic aggregates in the uterine muscle (8%), and pure lipomas (6%). Additionally, the cases were divided into three groups depending on the extent of fatty changes. Group 1 (48% of cases) consisted of cases in which less than 25% of the changes were present in the examined material. In group 2 (28% of cases) the fatty changes were between 25 and 50%. In group 3 (16% of cases) fatty changes constituted more than 50% of the examined specimen. The extent of adipocytic changes was connected with patient age, being significant between groups 1 and 3 (p < 0.01). Regressive stromal changes in leiomyomas occurred more often in middle-aged patients, with stage 2 lipomatosis than in other subgroups. Among 46 cases of UFLs two patients were diagnosed with a coexisting malignant uterine neoplasm (4.35%). In four patients with muscular lipomatosis, two were diagnosed with a coexisting malignant uterine tumor too (50%).

Conclusions: 1. Uterine fatty lesions are rarely diagnosed, although they occur more often than previously thought. 2. Mixed tumors predominate over pure lipomas. 3. The histogenesis of these lesions seems to be multi-factorial, considering the different types of UFLs. 4. The extent of uterine fatty metaplasia positively correlated with the age of operated women. 5. The coexistence of UFLs with other malignant uterine neoplasms is accidental.