1Departmemt of Family Medicine & Public Health, Sultan Qaboos University Hospital, Muscat, Oman; 2Department of Dermatology & Skin Science, University of British Columbia, Vancouver, British Columbia, Canada; 3Division of Dermatology, Faculty of Medicine, McGill University, Montreal, Quebec, Canada *Corresponding Author e-mails: a.alkhalili@hotmail.com and alkhalili2014@gmail.com انتباذ بطاين رمحي سري عايدة عبد اهلل اخلليلية و روبن بيليك Umbilical Endometriosis *Ayida A. Al-Khalili1,2 and Robin Billick3 A 43-year-old nulliparous woman presentedto a dermatology clinic in Montreal, Quebec, Canada, in 2015 with swelling and pain in the umbilical area which worsened and occasionally bled during menstruation. The onset of these symp- toms coincided with the discontinuation of oral contraceptive pills, which she had been taking for the last seven years. The patient complained of dysmenorrhoea and had no history of abdominal or pelvic surgeries. Upon clinical examination, multiple ill-defined bluish erythematous papules were noted in and surrounding the umbilicus [Figure 1]. A skin biopsy showed glandular proliferation with hemo- siderin deposition and myometrial stroma, consistent with a diagnosis of endometriosis [Figure 2]. A gynaecological evaluation revealed an ovarian cyst. She was treated with progestin which relieved the dysmenorrhoea and resulted in the regression of both the ovarian cyst and her umbilical symptoms. As most of the remaining umbilical nodules were small and remained asymptomatic, the patient did not wish to have them surgically removed. Comment Endometriosis refers to the presence of endometrial tissue outside of the uterine cavity. Extrapelvic or extragenital endometriosis has been described in several anatomical locations, including the skin, brain, lungs, gastrointestinal tract, urinary system and musculature.1 While umbilical endometriosis—also known as Villar’s nodule—is a rare site for endometriosis, it is the most common form of cutaneous endometriosis.2 There are many theories to explain the pathophysiology of umbilical endo- metriosis, including migration via the vascular or lymphatic vessels, metaplastic transformation and iatrogenic implants.2 Umbilical endometriosis is classified as primary if it occurs spontaneously or secondary if it results from iatrogenically-seeded endometrial implants following various surgical procedures, with the latter being more common.2,3 Umbilical endometriosis constitutes 3.2–40% of all extragenital endometrioses.2 Symptoms include umbilical masses with swelling and pain interesting medical image Sultan Qaboos University Med J, Aug 2017, Vol. 17, Iss. 3, pp. e371–372, Epub. 10 Oct 17 Submitted 19 Mar 17 Revision Req. 23 Apr 17; Revision Recd. 27 Apr 17 Accepted 25 May 17 Figure 1: Multiple erythematous papules on the lower umbilical area of a 43-year-old nulliparous woman. doi: 10.18295/squmj.2017.17.03.023 Umbilical Endometriosis e372 | SQU Medical Journal, August 2017, Volume 17, Issue 3 to each patient and will depend on the severity of symptoms and the coexistence of pelvic endometriosis.4 Suggested therapeutic options include various surgical procedures and treatment with hormonal therapy or danazol.2,4,5 References 1. Davis AC, Goldberg JM. Extrapelvic endometriosis. Semin Reprod Med 2017; 35:98–101. doi: 10.1055/s-0036-1597122. 2. Victory R, Diamond MP, Johns DA. Villar’s nodule: A case report and systematic literature review of endometriosis externa of the umbilicus. J Minim Invasive Gynecol 2007; 14:23–32. doi: 10.1016/j.jmig.2006.07.014. 3. Calagna G, Perino A, Chianetta D, Vinti D, Triolo MM, Rimi C, et al. Primary umbilical endometrioma: Analyzing the pathogenesis of endometriosis from an unusual localization. Taiwan J Obstet Gynecol 2015; 54:306–12. doi: 10.1016/j. tjog.2014.03.011. 4. Mechsner S, Bartley J, Infanger M, Loddenkemper C, Herbel J, Ebert AD. Clinical management and immunohistochemical analysis of umbilical endometriosis. Arch Gynecol Obstet 2009; 280:235–42. doi: 10.1007/s00404-008-0900-4. 5. Fancellu A, Pinna A, Manca A, Capobianco G, Porcu A. Primary umbilical endometriosis: Case report and discussion on management options. Int J Surg Case Rep 2013; 4:1145–8. doi: 10.1016/j.ijscr.2013.11.001. during menstruation and, to a lesser extent, bleeding.2 The differential diagnosis of the condition includes both benign and malignant tumours, such as primary and metastatic neoplasms, polyps, granulomas and keloids.1 However, the risk of malignant transformation is minimal.3 Currently, there is as yet no consensus on the optimal management strategy for umbilical endo- metriosis; therefore, treatment should be personalised Figure 2: Haematoxylin and eosin stain at x40 magnification showing glandular proliferation (black arrows) with hemosiderin deposition (white arrow) and myometrial stroma (arrowhead). These features were deemed indicative of umbilical endometriosis. https://doi.org/10.1055/s-0036-1597122 https://doi.org/10.1016/j.jmig.2006.07.014 https://doi.org/10.1016/j.tjog.2014.03.011 https://doi.org/10.1016/j.tjog.2014.03.011 https://doi.org/10.1007/s00404-008-0900-4 https://doi.org/10.1016/j.ijscr.2013.11.001