Primary umbilical endometriosis - Diagnosis by fine needle aspiration

A 38-year-old woman presented with a history of slowly growing blackish nodule over the umbilicus of 3 years duration. It was associated with cyclic pain during menstruation. No past history of abdominal surgery was noted. On examination, the nodule was 2 × 1.5 × 1 cm in size, soft to firm in consistency, brown to black in color, was tender on palpation and was non-reducible [ Figure 1a ]. Ultrasound abdomen showed multiple uterine intramural fibroids and ultrasound of the nodule showed well-defined anechoic area at the umbilicus. There were no other significant contributory findings. The preliminary diagnosis was umbilical endometriosis or Sister Joseph's nodule/melanoma. As a number of benign and malignant lesions come into clinical differential diagnosis, fine needle aspiration cytology (FNAC) was advised as the first line of investigation. FNAC from the umbilical nodule was performed using a 20-ml syringe and 23-gauge needle. The smears were stained with Papanicolaou (Pap) and May-Grünwald-Giemsa (MGG) stain. Patient subsequently underwent wide excision of umbilical lesion and abdominal hysterectomy for uterine fibroids. Aspirate revealed a moderately cellular smear comprising strips and sheets of endometrial epithelial cells with crowded nuclei and scanty cytoplasm [Figure 1b and c ]. Endometrial stromal cells were scanty. No atypia or atypical mitosis was noted. Aspirated specimen also included degenerated red blood cells and hemosiderin laden macrophages [ Figure 1d ]. A cytodiagnosis of umbilical endometriosis was made. Histopathological examination of the excised umbilical nodule confirmed the same [ Figure 2 ]. Peroperatively, there was no evidence of intra- and extrapelvic endometriosis anywhere else. Patient is asymptomatic after 1 year of follow-up. (a) Photograph showing brown nodule at the umbilicus. (b) Microphotograph showing strips and sheets of endometrial epithelial cells and stromal cells in the background (Pap, ×100). (c) Microphotograph showing crowded nuclei and scanty cytoplasm (Pap, ×400). (d) Microphotograph showing endometrial cells and hemosiderin laden macrophage (arrow) (MGG, ×100) Microphotograph showing endometrial glands and stroma (H and E, ×100)

Primary (spontaneous) umbilical endometriosis was first described by Villar in 1886 and represents about 0.5-1% of all cases of extragenital endometriosis.[ 8 – 10 ] Endometriosis involving the abdominal wall is termed as cutaneous endometriosis and is commonly associated with surgical scars.[ 8 ] Clinically, the lesions appear as firm nodules varying in size from a few millimeters to centimeters. Cyclical pain with a palpable mass is the most common presenting symptom. The pathogenesis of endometriosis has been a topic under constant debate during the last decade. Sampson hypothesized in 1920s that endometriosis resulted from retrograde menstruation through the fallopian tube into the pelvis.[ 4 ] However, several other theories exist for the development of endometriosis, including coelomic metaplasia, direct spread, iatrogenic dissemination, and lymphatic or hematogenous spread.[ 2 ] The theory of lymphatic and hematogenous transplantation is favored in the case of umbilical endometriosis with coexisting pelvic endometriosis. However, it is believed that the disease might arise through metaplasia of urachus remnants in case of isolated umbilical endometriosis.[ 8 ] Those patients commonly present with a brownish or bluish painful umbilical nodule, as noted in our patient. A few series have reported bleeding from the nodule. A slow-growing umbilical mass associated with cyclical pain during menstruation and brown color gives a picture clinically characteristic of cutaneous endometriosis.[ 11 ] However, only 75% of patients have their symptoms associated with the menstrual cycle. Because characteristic symptoms are not always present, clinical diagnosis of umbilical endometriosis can be difficult. So, when a mass develops at the umbilicus, the possibility of endometrioma must be kept in mind although it may be mistaken for suture granuloma, lipoma, abscess, cyst hernia, and nonmalignant melanocytic tumors.[ 2 10 ] The cytology smears are generally cellular with epithelial and stromal fragments admixed with hemorrhage and hemosiderin laden macrophages.[ 5 – 7 ] The cytologic features of cutaneous and subcutaneous endometriosis are related to cyclic hormonal changes.[ 2 7 ] In proliferative phase, the epithelial cells form cohesive sheets of uniform, small cells with scant cytoplasm, round to oval nuclei with bland chromatin and occasional non-atypical mitotic figures. During secretory phase, the cells show a gradual increase of the cellular size and microvacuolation is observed. In the same way, the stromal cells reveal more abundant cytoplasm as the hormonal cycle progresses and may undergo pre-decidual changes showing an epithelioid appearance that can cause diagnostic difficulties. Also, in the second phase of the cycle, a prominent vascular network may be observed closely associated with the stromal fragment. The background is generally sanguineous and contains a variable proportion of lymphocytes, neutrophils and histiocytes. The mesenchymal component is scant, with small fragments of adipose tissue and fibrous tissue with a different grade of collagenisation representing the tissue where the ectopic endometrium is set. FNAC smears can be hemorrhagic, showing only a few macrophages and inflammatory cells in which case endometriosis may be missed. If only endometrial stroma is picked up, it could be mistaken for a stromal neoplasm. If nuclear atypia is seen, the mass should be excised and evaluated to rule out malignancy. The imaging modalities are nonspecific, but are useful in determining the extent of the disease and planning of operative resection, especially in large and recurrent lesions.[ 1 ] Due to the typical cyclical pain and clear-cut cytomorphological features, cytological diagnosis of umbilical endometriosis was rendered without any difficulty in this patient. Thus, FNAC is a fast and accurate method to make the diagnosis before surgery, avoiding errors in approach of the umbilical nodules.

Endometriosis was first described by Rokitansky in 1860 and was defined as the presence of proliferation of endometrium outside the uterine cavity, commonest site being the pelvis.[ 1 ] It is a common gynecological condition that affects up to 22% of all women, 8-15% of women of reproductive age and 6% of premenopausal women.[ 2 3 ] Deposits of endometriosis occur frequently anywhere in the pelvis including vulva, vagina, cervix, ovaries, pelvic peritoneum, and less commonly (12%) in the extrapelvic sites including intestinal tract, urinary tract, peritoneum, omentum, lung, thoracic cage, surgical scars, abdominal wall, inguinal region and umbilicus. The majority of the reported cases occurred in gynecologically induced abdominal or pelvic scars, including hysterectomy, episiotomy, cesarean section and laparoscopy.[ 2 – 7 ] Few cases of spontaneous umbilical endometriosis have been reported.[ 2 8 9 ]