LAUSR

Cutaneous endometriosis represents 1-5% of endometriosis cases and typically appears in the umbilicus and/or abdominal scars [1-3]. It is classified as primary or secondary depending on its pathogenesis. Primary cases are idiopathic and diagnosed based on exclusion, whereas secondary cases are always related to cutaneous implantation from previous surgeries (mainly Caesarean sections). Primary cutaneous endometriosis, also known as Villar’s nodule, is much more uncommon than secondary cases and, to the best of our knowledge, less than 40 cases have been published in the English literature [4]. The differential diagnosis of umbilical nodules includes cutaneous metastasis (classically known as “Sister Mary Joseph’s nodule”), umbilical hernias, keloids, urachal and omphalomesenteric duct cysts, nodular melanomas, pyogenic granulomas and primary umbilical adenocarcinoma [4]. Histopathological analysis is always mandatory in these nodules for a correct diagnosis and to exclude primary or secondary cutaneous malignancies. Immunohistochemical staining for CD10 and oestrogen and progesterone receptors is particularly helpful in cutaneous endometriosis in order to highlight both the stroma and the cylindrical epithelium, respectively. Lastly, dermoscopy has also been reported to be helpful in the differential diagnosis of umbilical nodules although its diagnostic potential is much more limited [5]. The treatment of choice of cutaneous umbilical endometriosis is surgical excision with wide margins to reduce the risk of recurrence. Medical treatment with agonists or contraceptive hormones may be considered for patients who do not desire surgery. Other therapeutical alternatives that have been reported are sclerotherapy, chemical cauterisation, laser vaporisation, percutaneous cryocoagulation and ablation by high-frequency ultrasound [4].