A Painful Periumbilical Nodule in a Reproductive-aged Woman

A 34-year-old premenopausal female presented with a chronically painful umbilical nodule. The patient’s past medical history was notable for eczema and a seizure disorder. She first noticed chronic symptoms of catamenial abdominal pain, bloating, and cramps. She was previously diagnosed and treated for gastroesophageal reflux disease; however, her pain continued to increase. This led to a general surgery referral discovering an umbilical hernia via a computed tomography scan. Despite laparoscopic hernia repair, she noted an intermittent small mass that increased in size and developed intense pain and pruritus in the periumbilical area. She was subsequently referred to a dermatologist. On physical examination, an asymmetric, irregular, irritated, and painful lesion was observed [Figure 1]. A shave biopsy to the dermis level was performed on the upper umbilicus. The histopathologic evaluation found scar-like fibrosis within the dermis and glandular structures embedded within a cellular and edematous inflamed stroma and extravasated erythrocytes [Figures 2 and 3].Figure 1: Clinical photograph Hyperpigmented umbilical subcutaneous nodule of about 2.0 × 2.0 cm in sizeFigure 2: Dermis with scar-like fibrosisFigure 3: Glandular structures within a cellular and edematous inflamed stromaWhat is the Diagnosis? Cutaneous endometriosis. Discussion Endometriosis is the ectopic proliferation of endometrial glands or stroma that usually lines the uterine cavity.[1] Cutaneous endometriosis is an uncommon extrapelvic manifestation representing 0.5% to 1.0% of all patients diagnosed with ectopic endometriosis.[2] The umbilicus is the most common location for cutaneous endometriosis representing 30 to 40% of cases.[2] The classic clinical presentation involves a reproductive-aged woman with a prior history of surgery that reports cyclical pain and swelling during menstruation, a blue, black, brown, or red subcutaneous palpable mass, and hemorrhage from the affected site.[1] The preferred method for definitive diagnosis of cutaneous endometriosis is histopathology via skin biopsy.[3] In our patient, the initial diagnosis was thought to be a keloid resulting from aberrant wound healing from a previous surgical procedure. The pathophysiology of a keloid involves a prolongation of the fibroblastic stage of wound healing driven by transforming growth factor-beta and platelet-derived growth factor.[4] Excessive proliferation leads to the overproduction of collagen and cytokines. Patients of African, Asian, and Hispanic descent have higher incidences of keloid development when compared to Caucasians.[4] The incidence in this population is estimated to be between 4.5% to 16%.[4] Due to the similar macroscopic presentation between keloids and cutaneous endometriosis, biopsy with histopathologic evaluation is the primary strategy to differentiate between these two entities. The characteristic histopathologic findings for keloids included increased whorls of thickened, hyalinized collagen bundles, known as keloidal collagen.[4] When a specimen lacks keloidal collagen, the following four diagnostic criteria are used to diagnose a keloid: a standard epidermis and papillary dermis, a “tongue-like” advancing edge below the papillary dermis, a horizontal fibrous band in the upper reticular dermis, and a prominent fascia like a band in the deep dermis.[4] Keloids are typically diagnosed clinically; however, a biopsy is required in situations where the diagnosis is in question, like in our patient. Typically, once a primary or secondary cutaneous endometriosis diagnosis is made, the standard treatment is surgical excision with regular follow-up. If the patient prefers nonsurgical treatment, we can offer gonadotropin-releasing hormone antagonist medication (such as elagolix or leuprolide) or danazol.[3] In many cases, hormonal therapy and surgical excision are used synergistically with excellent clinical outcomes and low recurrence rates. In one retrospective study by Vellido-Cotelo et al., only 2 of 17 patients (14%) with scar endometriosis had pelvic endometriosis.[5] This is similar to the incidence of pelvic endometriosis in the general population. Thus, the role of gynecology primarily depends on if the patient has more classic symptoms of pelvic endometriosis, such as dysmenorrhea, dyspareunia, abnormal flow, or infertility.[3] The prognosis for cutaneous endometriosis is favorable, with a low rate of recurrence or malignant transformation. Learning points Cutaneous endometriosis is a rare manifestation of endometriosis, the development of endometrial glands and stroma outside the uterus, which constitutes less than 1% of total cases of this gynecological condition. The typical presentation of cutaneous endometriosis is nonspecific, presenting as a painful, firm subcutaneous papule or nodule, with the umbilicus being a common location. The differential diagnosis for these lesions is broad and includes a hematoma, hernia, lipoma, scar granuloma, keloid, or a cutaneous metastasis of cancer (such as a Sister Mary Joseph Nodule).[4] It can be challenging to distinguish between these diagnoses, but the association of cyclical pain with menstruation would support cutaneous endometriosis. Histopathology via skin biopsy is the preferred method for a definitive diagnosis of cutaneous endometriosis. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.