Spontaneous cutaneous endometriosis in Mons Pubis: review of literature

Cutaneous endometriosis is not a very often seen condition and is broadly classified as primary (spontaneous) and secondary. While perineal endometriosis arising in a previous scar has been reported, spontaneous cutaneous endometriosis in perineum is extremely rare and only three cases occurring in mons pubis have been reported in literature. We report a case of 34-year-old lady presented with a swelling in pubic region and associated dull aching pain of 1-year duration with no history of cyclical variation of symptoms. Investigations finally concluded a diagnosis of endometriosis and a Complete excision with clear margins. Clinicians should be aware that a spontaneous endometriosis in the perineum can occur and can have atypical presentation with no increase in size or pain during menstruation.

Endometriosis, Cutaneous, Spontaneous, Mon pubis, Perineum

Endometriosis is the abnormally implanted normal endometrial mucosa in locations other than the uterine cavity. It manifests as dysmenorrhoea, menorrhagia, chronic pelvic pain, dyspareunia and infertility. These debilitating symptoms compound together to cause significant social and psychological impact on the lives of women. Endometriosis affects 3–10% of women of reproductive age group. The ectopic endometrial tissue primarily affects the peritoneum, ovaries and rectovaginal septum.1 Rarely, a previous episiotomy scar can form a nidus for such ectopic endometrial tissue leading to cutaneous endometriosis in the perineum and vulva.2,3 However, it is extremely uncommon to find a spontaneous cutaneous endometriosis without a pre-existing surgical scar. In this case report, we present a rare spontaneous endometriosis in mons pubis, which was successfully treated. To the best of our knowledge, only 03 cases of occurrence in mons pubis and 06 cases occurring in the combined location of mons pubis, vulva inguinal and perineum have been reported in literature. Case report A 34-year-old female patient (P1L1) presented with a swelling in her pubic region associated with dull aching pain for 1 year. The swelling was insidious in onset, and she denied any history of cyclical increase or regression in its size with menstrual cycles. She did not have any history of cyclical pain associated with the swelling/dysmenorrhoea/menorrhagia or dyspareunia. It was irreducible and did not increase in size with cough or straining. She had no history of pelvic surgery, episiotomy, instrumentation or trauma around the mons pubis region in the past. There was no history of similar swelling or endometriosis in the family. On evaluation, there was a 2 × 2 cm irreducible, nontender, immobile, nonpulsatile swelling on the left side of the mons pubis (Fig. 1). An ultrasonography of the perineum revealed a 19 × 15 × 17 mm ill-defined hypoechoic lesion in the subcutaneous plane of anterosuperior to the left labia majora, which showed increased vascularity on colour doppler. On magnetic resonance imaging (MRI) correlation, the lesion appeared iso-intense to muscle on T1, T2 (Fig. 2A and B) and hyperintense on T2 fat suppression (T2 FS) with hyperintense surrounding fat on short tau inversion recovery sequences. The differential diagnoses given were (a) evolving abscess of left labia majora, (b) infected hydrocoele of Canal of Nuck and (c) benign mesenchymal tumour. A fine needle aspiration cytology was done, which was suggestive of a benign glandular lesion, probably endometrioma. The lesion was excised under local anaesthesia. The lesion was densely adhered to the surrounding tissue and was excised with clear margins. The post op period was uneventful, and the wound had healed completely on her OPD follow-up on post op day 7. The histopathology confirmed the lesion as endometriosis (Fig. 3A and B). The patient experienced a better quality of life after the surgery and did not have recurrence during her follow-up at 1 month, 6 months and 1 year. Written informed consent was taken from all the subjects before recruitment for the study.

Endometriosis is benign gynaecological condition, which is rather poorly understood due to nonavailability of a suitable animal model. This condition was documented in ancient medical texts more than 4000 years ago. Historically, women with symptoms of endometriosis were considered mad, weak, immoral, promiscuous or hysterical and were subjected to treatment with leeches, straitjackets, bloodletting, chemical douches, genital mutilation, impregnation, hanging upside down and even killing due to suspicion of demonic possession.4 Hippocratic doctors recognized the symptoms as a true organic disorder 2500 years ago and documented it in the Hippocratic Corpus. It was first discovered microscopically by Karl von Rokitansky in 1860.5 The ectopic endometrial tissue possesses steroid hormone receptors akin to normal endometrium and responds to the cyclical hormonal environ in the backdrop of menstruation. Various theories have been postulated to explain the disease, but none has been proven in toto.6 Retrograde menstruation, metaplasia, lymphovascular spread and genetic predisposition are the leading theories that currently exist. The most plausible explanation for a spontaneous endometriosis in mons pubis in our patient is the lymphatic spread of ectopic tissue via the inguinal lymph nodes by the way of iliac lymph nodes. Other possible explanations could be retrograde menstruation or metaplastic changes in the Canal of Nuck, which may seed an ectopic focus spontaneously in the mons pubis. However, in the absence of a hernia of the Canal of Nuck in our patient, these may be remote possibilities. Some women are genetically predisposed to endometriosis and may explain a spontaneous endometriosis at the mons. Our patient did not have a family history of endometriosis and therefore may not have been genetically predisposed. This patient had an ectopic endometrial tissue in the mons pubis and did not have any history of instrumentation or a predisposing scar in the area. Spontaneous endometriosis of the perineum is extremely rare. Only six cases of spontaneous perineal endometriosis have been reported that did not have a predisposing episiotomy scar or perineal/pelvic surgery (Table 1). Table 1. | Sl no | Author | Year | Age | Symptoms | Management | Follow-up | |---|---|---|---|---|---|---| | 1 | Su HY | 2004 | 15 | Vulvar swelling | Local excision | 4 m; no recurrence | | 2 | Aydin | 2011 | 28 | Vulvar pain | Local excision | Not mentioned | | 3 | Nasu K | 2013 | 39 | Perineal swelling and cyclical pain | Local excision | 5 m; no recurrence | | 4 | Peer M | 2013 | 44 | Swelling in the mons pubis | Excision + chemoradiotherapy for malignant changes | 3 y; no recurrence | | 5 | Zhai J | 2014 | 41 | Swelling in the mons pubis and cyclical increase in size and pain | Not mentioned | Not mentioned | | 6 | Lo L | 2018 | 46 | Swelling in mons with cyclical pain | Local excision | 1 y, no recurrence | | 7 | Present case | 2019 | 34 | Swelling in mons with dull aching pain | Local excision | 1 y, no recurrence | They present as red, brown or bluish-black cystic swelling that intermittently increases in size and develop tenderness during menstruation. Patients may also complain of dyspareunia, discharge and chronic pelvic pain.7 Surprisingly, our patient did not have symptoms that increased during menstruation. It did lead to initial doubts of this being an endometriosis and was thus referred by the gynaecologist to the surgeons. Agarwal et al have emphasized that this cyclical change may not be present in every case, and it is not essential for the diagnosis.8 Concomitant pelvic endometriosis has been reported to be around 17% in one study.9 So, should cases of spontaneous endometriosis be investigated to rule out a concomitant endometriosis? The consensus is that in the absence of symptoms suggestive of endometriosis, it is presumed that it is an isolated cutaneous endometriosis. Those who do have a suggestive history should undergo a diagnostic laparoscopy. Imaging with transvaginal ultrasonography and MRI of the pelvis help in delineating the swelling and show associated peritoneal/pelvic endometriosis, if present. Histological examination with a core needle biopsy helps clinch the diagnosis and typically reveals non ciliated columnar epithelium-lined tubular glands and hemosiderin laded macrophages surrounded by a cellular fibrotic stroma. The dependence of the ectopic endometrial mucosa on the cyclic hormonal milieu provides the basis for medical therapy with GnRH agonists, progestins, oral contraceptive pills, androgen and aromatase inhibitors. However, reports in literature on spontaneous perineal endometriosis have favoured surgical resection with clear margins over medical management as a definite treatment approach (Table 1). While recurrence after cessation of medical treatment is invariable,10 recurrence of cutaneous endometriosis after excision are low and has been reported between 0 and 8% in studies that have a minimum of 1 year of follow-up.11, 12, 13 Malignant changes, although rare, have been reported and surgery prevents this potential danger.14,15 In our case, a surgical excision was curative with complete resolution of symptoms, improved the quality of life and no recurrence.

In conclusion, we would like to emphasise that clinicians should be aware that a spontaneous endometriosis in the perineum can occur and can have atypical presentation with no increase in size or pain during menstruation. Disclosure of competing interest The authors have none to declare.

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