Sister Mary Joseph’s Nodule (SMJN) is a rare physical sign of metastatic abdominopelvic malignancy, characterized by a malignant umbilical nodule. Umbilical skin metastases are relatively uncommon in clinical practice, with an incidence ranging from 1 to 3%, and they are typically associated with gastrointestinal or genitourinary cancers [1]. In approximately 30% of cases, the primary source of the neoplasm remains unidentified [2].

The presence of SMJN can occur at the time of diagnosis or during disease recurrence, and it is strongly indicative of a very poor prognosis [3]. These nodules are often a late manifestation of extensive abdominopelvic malignancy.

In this report, we present an original case of a patient who was diagnosed with metastatic serous ovarian cancer and subsequently developed periumbilical nodules during the course of the disease.

SMJN is the term used to describe metastatic nodules found in the umbilical region, and it is most commonly seen in cases of gastrointestinal or gynecological cancers. The name "Sister Mary Joseph's nodule" originated from a nurse named Julia Dempsey, also known as Sister Mary Joseph, who worked as an assistant to Dr. William J. Mayo at Saint Mary's Hospital, which is now known as Mayo Clinic, in the United States. She was the first person to observe the connection between periumbilical nodules and intra-abdominal malignant tumors, although the first official description was documented by Hamilton Bailey in the 11th edition of his book, "Physical Signs in Clinical Surgery" [4].

The mechanism of tumor spread in this context remains poorly understood. Due to its vascularity, connections to embryological remnants, and proximity to the peritoneum, the umbilicus is predisposed to metastatic involvement. For this reason, several hypotheses regarding the pathogenesis have been proposed, including direct invasion of the peritoneum, accidental implantation following surgery, lymphatic or hematogenous spread, or via embryonic remnants in the abdominal wall [5].

The most common primary sites associated with umbilical nodules are usually gastric cancer (30%), colorectal cancer (25%), and pancreatic cancer (18%) in men. In women, the most frequent primary locations are ovarian cancer (34%), endometrial cancer (12%), and colorectal cancer (12%) [1]. Other rare causes have also been reported, such as lymphoma [6] and metastatic prostate cancer [7].

Not all umbilical nodules represent malignant tumors. In some cases, they can be present in benign conditions, and the differential diagnoses should include umbilical hernia, cutaneous endometriosis, and benign tumors like dermatofibromas, papillomas, myxoma, and foreign body granulomas [8]. Since several benign conditions can mimic umbilical metastasis, histological examination of the umbilicus is not only crucial but also guides clinicians in searching for the potential primary site.

While SMJN is a relatively uncommon clinical finding, occurring in only 3% of metastatic cancers, it has been described in recent case reports. In the largest case series involving 34 patients from a university hospital in Tanzania, males outnumbered females by a ratio of 1.4:1. Most patients (70.6%) presented with large umbilical nodules measuring more than 2 cm. The stomach (41.1%) was the most common primary tumor site, with ovarian cancer accounting for 5.9% of SMJN cases [9]. Adenocarcinoma was the most frequently observed histological type in that case series. Since all patients had advanced and metastatic disease, only palliative therapy was provided, resulting in a mortality rate of 32.4%.

Although umbilical metastasis in cases of serous ovarian cancer has been previously reported in the literature [5,10,11], our case differs in several important aspects. SMJN can be present at the time of diagnosis or manifest during disease recurrence. In our case, the umbilical mass was the initial presentation, leading to the diagnosis of metastatic serous ovarian carcinoma. This finding emphasizes the importance of vigilance among clinicians.

Typically, the clinical presentation of SMJN is characterized by an irregular palpable nodule that is often painful, rapidly growing, and of firm or elastic consistency. The nodule may be ulcerated with bloody, purulent, or serous discharge. It can also present as an induration of the subcutaneous tissue [12]. In our case, the umbilical mass appeared to be deeper and was not clinically apparent to the patient due to its painless nature and slow growth.

In cases of isolated umbilical mass, imaging plays a crucial role in establishing a diagnosis. Additionally, fine needle aspiration cytology or core biopsy is necessary as a simple, fast, accurate, and cost-effective diagnostic tool. Histological and immunohistochemical investigations are essential in confirming the diagnosis [13]. The most common histological type is adenocarcinoma (accounting for approximately 75% of cases), while epidermoid, undifferentiated, or carcinoid types are less common. Furthermore, immunohistochemical markers are crucial in determining the origin of unknown primary cancer. In our case, the positivity of monoclonal antibodies such as cytokeratin 7, WT1, and RE suggests a serous ovarian origin.

The prognosis for patients presenting with SMJN is generally poor, as its presence typically indicates advanced and disseminated malignancy, with a mean life expectancy ranging from 2 to 11 months without treatment [14].

The management of the disease should consider patient preferences, clinical condition, and the nature of the primary malignancy. Often, palliative care may be the only option for some patients, as demonstrated in our case presentation. However, in carefully selected cases, more aggressive treatments such as surgery, chemotherapy, and radiotherapy may be beneficial [2]. The patient in this case did not receive any treatment and is currently undergoing strict follow-up without complications.