Atypical Presentation of Rare Disease Leiomyomatosis Peritonealis Disseminata Effectively Managed by Aromatase Inhibitor

Introduction: Leiomyomatosis peritonealis disseminate (LPD) is a rare disease of unknown etiology (only <200 cases reported), suspected to originate from a metaplasia of sub mesothelial multipotent mesenchyme cells with multifocal origin interspersed most commonly in abdominal cavity. The clinical picture simulates disseminated malignancy primarily followed by definitive diagnosis by histopathology. LPD shows predominant distribution in non-Hysterectomized reproductive age group. Background: The probable etiopathogenesis proposed is smooth muscle metaplasia under influence of exogenous and endogenous gonadal steroids predominantly estrogen (e.g., Pregnancy, HRT, OC pills, hormone secreting ovarian tumors, Obesity etc.). Also, usage of laparoscopic power morcellator in the past has been implicated as causative factor. Expected treatment for LPD is if non-hysterectomized–abdominal pain hysterectomy followed by excision of lesions (Debulking) and omentectomy in addition to discontinuation of existing hormonal inputs. Case: A 53-year-old woman 13 years post hysterectomy was referred to our hospital as suspected case of lymph proliferative disorder (NHL) with incisional hernia. On CT Large masses were seen in abdominal cavity with provisional diagnosis stated as? Lymphoma or? Castleman’s disease. Hence Incisional biopsy of mass was done with HPE report showing LPD with IHC for α-smooth muscle actin-positive, CD117 negative, ER/PR-positive. In view of hormone receptor positive status and absence of significant symptoms attributable to tumor mass, the woman was planned for anti-estrogen therapy with Aromatase inhibitors (Letrozole 2.5 mg 1-0-0) with regular periodic follow up along with oral calcium supplementation and 6 monthly Inj. Zolendronic acid. CT findings after 1 year showed 31% regression in size of lesions compared to previous one. Conclusion: The case here presented was atypical in all sense in accordance with present literature available as mentioned below. The patient was not on exogenous estrogen supplementation and there was no source of endogenous estrogen except adrenals as patient had undergone pan abdominal hysterectomy. Also, BMI was in normal range. There was neither history of Endometriosis nor implication of Laparoscopic power morcellator in the past. No debulking surgery was done but only managed conservatively with medications. Here the pivotal role of estrogen in causation was considered. Therefore, it was decided to start aromatase inhibitor –Letrozole (mechanism inhibits peripheral conversion of androgen to estrogen. As expected, there was dramatic response to therapy showing regression in size of masses confirmed on CT.