A particularly bothersome umbilical nodule

C: Cutaneous endometriosis.

Based on the patient's history and physical examination, which one of the following is the most likely diagnosis [ Table 1 ]? Sister Mary's Joseph nodule Pyogenic granuloma Cutaneous endometriosis Nodular melanoma Sister Mary's Joseph nodule Pyogenic granuloma Cutaneous endometriosis Nodular melanoma Selected differential diagnosis of cutaneous endometriosis

Cutaneous endometriosis is a rare phenomenon, representing approximately 0.5-1% of all cases of ectopic endometrial tissue. Cutaneous endometriosis may arise spontaneously within the umbilicus, but the majority of lesions develop on surgical scars of the abdominal and genital region, after transplantation of viable endometrial cells at the time of surgery, in women of reproductive age.[ 1 ] It should be suspected in any woman with a nodule near the umbilicus who presents with pain, itch, odor, swelling and bleeding associated with the menstrual cycle. The cyclicity is not always demonstrable and it is not essential for diagnosis. These symptoms are the consequence of extravasation of blood and menstrual debris from the endometrial glands into surrounding tissue. Diagnosis is commonly made by histopathology that shows endometrial glands in proliferative or secretory phase [ Figure 2 ]. Management includes both surgery and hormone suppression. The combined oral contraceptive pill, progestogens and gonadotropin-releasing hormone analogs have been attempted. Simultaneous laparoscopy for the diagnosis of a coexisting pelvic endometriosis is mandatory in cases of recurrent symptoms.[ 2 ] Sister Mary Joseph's nodule is referred to as metastatic lesion of the umbilicus. Most of the tumors are adenocarcinomas originating from gastroenteric and genital tracts, but there are a considerable number of cases in which the primary tumors were unknown. Clinically, the lesions are firm, indurated plaques or nodules, usually with vascular appearance. Sometimes, the lesions are fissured or ulcerated with discharges. On histological examination, the vast majority (95%) of the tumors are adenocarcinomas.[ 3 ] Pyogenic granuloma (lobular capillary hemangioma) is a common reactive angiomatous proliferation that occurs in the skin and mucous membranes. It occurs spontaneously, but usually as a result of traumatic insult to the skin. Histopathological exam: Ectopic endometrial glands with surrounding cellular stroma, occasionally associated with extravasation of erythrocytes embedded in the stroma and some acute inflammatory infiltrates around the glands (×40) In the initial phases it appears as a red or reddish-brown sessile papule, pliable to touch and painless. Successively it rises, becoming dome-shaped and sometimes evolving into a nodule, also peduncolated. The evolution is rapid and after some weeks it becomes stable. One almost constant feature of the lesion is bleeding at minimal trauma. Histologically, pyogenic granuloma consists of numerous blood vessels and inflammatory cells embedded in the edematous stroma.[ 4 ] Nodular melanoma is typically a discrete dark black/brown nodule; ulceration and bleeding are late complications. Also, in nodular melanoma, although it is acromic, usually you can find small areas of pigmentation that can be directed toward a melanocitic lesion. It is more common in men than women and it has a peak incidence around 50 years of age.[ 7 ] Nodular melanoma arises in normal skin or in a precursor lesion and it increases significantly its size in a short period of time. A widely accepted histopathological definition of nodular melanoma is a melanoma that lacks an in situ component beyond three rete ridges of the invasive vertical growth phase; thus, even in its early stages, nodular melanoma has the potential to metastasize.[ 8 ]