It’s about time I research more about Endometriosis being found in places other than your pelvic region.  We’ve already covered lungs, spine, and eyes, and today we’re going to delve into cases of Endometriosis and skin.  Skin? Yes, skin.  I’ve read that it’s rare, just like the other areas outside of the pelvic cavity…but, it does occur.  Some theorize it is implanted via the lymphatic orpro vascular systems; others think the cells are transplanted via surgery.

There seem to be two common categories of Endometriosis and the skin : spontaneous Endometriosis and scar Endometriosis.  Spontaneous Endo simply appears in random places on healthy skin (cutaneous or subcutaneous).  Scar Endo is found within scar tissue from prior surgeries or injuries.  It appears that surgical excision/removal of the Endometriosis lesions from the skin is the most common and effective way of handling the lesions.  Some surgeries may leave defects, which may (or may not) be repaired or rebuilt with a surgical mesh.  Some studies suggest that hormonal treatment may be too harsh for the patient for solitary lesions.

The first recorded case of Endometriosis (or an endometrioma) in the belly button was reported in 1886, and was referred to as a “Villar’s Nodule,” named so after  Dr. Francis Villar.  It’s described in his publication Tumeurs de L’ombilic. You will still find credit and citations to Dr. Villar in many current studies and reports regarding cutaneous Endometriosis.

A study presented in 1967 involved a 27-year-old woman who complained of pain and discharge from her anus during her periods.  Upon close inspection, nodules were discovered on her anal sphincter.  They were surgically removed and biopsied, and Endometriosis was confirmed.  Unfortunately, I do not have access to the entire article and cannot recant how her recovery ended.  But…the anus? Ugh. It’s everywhere… (insert “pain in the ass” joke here).

A study published in 1995 focused around a 46-year-old woman who had complained of a “nodule” on her belly button for the past year and abdominal pain for the past two years.  Her belly button would occasionally bleed.  She had no prior surgical history, did not take birth control, and did not complain of painful periods.  The nodule was surgically removed, biopsied, and Endometriosis was discovered.  After the removal of the mass, she did not have any recurrence.

A study was published in 2007 where a 47-year-old woman had complaints of a darkened  spot on her caesarean scar, which became increasingly painful during her periods.  She had her caesarean delivery 12 years prior, and had no previous health issues.  Upon inspection, beneath the discoloration was a small, subcutaneous mass.  An initial incision biopsy of the mass’s tissues revealed the presence of Endometriosis, and the mass was excised.  Endometriosis can be found in many scars, and because hers took 12 years to manifest, physicians reported, “[t]his leads us to the hypothesis that the mechanical migration theory played an important role in the development of the disease, since it appeared on the caesarean scar (a low-resistance point) after many years.”

In 2009, a 46-year-old woman was reported to have a lesion in her umbilicus (aka belly button), which had a little black “mass.”  It was surgically removed and biopsied…the results were consistent with Endometriosis.  One theory as to why Endo grows in your belly button is that the cells were transferred during abdominal surgery and unknowingly deposited there…however, this woman had no history of abdominal surgeries.  She also did not have any abnormal menstruation history .  It was a mystery.  Eighteen months later, she had no recurrent growths or symptoms.  A photograph of the black mass in her belly button can be seen by clicking the Acta Dermato Venereologica article under “Resources.”

In another study published in 2009, a 36-year-old woman would swell and bleed from her belly button during her monthly cycles.  The surgeons removed the mass from her umbilicus, which was biopsied and the presence of Endometriosis was confirmed.  A year later, she was still free of recurrent symptoms.

A 2010 study analyzed the case files of 376 women who were treated at the Fundacion Jimenez Diaz in Madrid, Spain.  Of those, 15 were treated for cutaneous Endometriosis.

In 2011, a 15-year-old girl went to the Emergency Room with complaints of pain and swelling to her vulva.  She had suffered an abrasion (they don’t go into details of “how”), 11 months prior.  The E.R. suspected Herpes due to the presence of lesions and treated her for such.  Regardless, her Herpes test came back negative.  After recurring symptoms of the same issues, biopsies were performed of the lesions found on her vulva, and were determined to be Endometriosis.  Unfortunately, her specific treatment at the E.R. is a common occurrence for many Endo sufferers who go to the E.R. : an STD is initially insinuated and tests are run, resulting in humiliation and a general sense of mistrust for the medical community.

A study published on May 1, 2015, in the Journal of Clinical and Diagnostic Research highlights an 18-year-old girl had begun to bleed from her fingertip during her menstrual cycle.  Her pelvic and rectal examinations were normal, but her fingertip had a small, discolored lesion, which had a distinct point which would continuously ooze blood during her periods over the past three months.  Due to financial issues, she could not afford to have an MRI or exploratory laparoscopic surgery of her abdomen.  Instead, doctors decided to biopsy the tissue around the lesion on her finger.  Lo and behold : Endometriosis.  The surgical excision of the lesion on her finger resolved her bleeding finger completely.  If you’d like to see a photograph, please feel free to click on their article referenced under “Resources” below.

A 2016 published case report was of a 49-year-old woman who had her gall bladder removed laparscopically in 1991.  In 2012, the muscle area beneath her belly button had become very painful.  She was previously diagnosed with painful periods and Endometriosis and she insisted on hormone therapy, which helped reduce her painful symptoms.  Two years later, the mass had grown to approximately 30mm (a little bigger than an inch) beneath her belly button and she had it surgically removed.  It was biopsied and confirmed as Endometriosis.  Although Endometriosis has been known to transfer during Endometriosis excision surgeries, this is the first report (as far as the authors know) of the tranferrance occuring during a gall bladder removal surgery.

A 2017 article discusses a 30-year-old woman with no history of Endometriosis or prior surgeries.  She was on Depo Provera and 9 months after stopping the contraceptive, she developed painful, bleeding little brown lumps in her belly button (this study has photos!).  They bled when she was on her period.  She had been to several physicians complaining of the bumps and had most recently been diagnosed with contact dermatitis and given creams.  When those didn’t work, she was referred to a dermatologist.  They took a shave biopsy of the bumps and they came back positive as Endometriosis.  She was then referred to a plastic surgeon to remove the bumps and a gynecologist to look further into a possible Endometriosis diagnosis.  Unfortunately, the study ends there.  The authors of this study stress the importance of conducting biopsies of masses before offering any type of diagnosis.

A 2017 abstract is about a woman who complained of a nodule in her belly button that bled while she was on her period.  Her physicians treated it as if it was a keloid scar, with cortisone injections.  But when those didn’t help, they suspected umbilical endometriosis.  A biopsy was performed on the nodule and confirmed as Endometriosis.  She was referred to her gynecologist for further treatment.

A study published in August 2017 was of a 29-year-old woman who had a nodule in her belly that would swell and bleed when she was on her period.  She had her appendix removed when she was 6 years old.  Imaging studies led to an exploratory laparoscopy.  They found extensive Endometriosis and excised it, as well as the lump from her belly button, which was biopsied and confirmed as Endo.

An October 2017 study follows the tale of a 49-year-old woman who had a lump develop in her belly button.  It would swell, bleed, and stink during her period…and she had it for the past six years!  She had delivered four children naturally…no c-sections involved…and had no prior history of Endometriosis or irregular periods.  She opted to have the lump removed surgically; it was excised and biopsied and confirmed as Endometriosis.  She received no further treatment.  And two years after her surgery, it had not returned.  Magically-spontaneous Endometriosis o’the navel.

In September of 2018, another study was published of a woman who had an appearance of a blotch in her belly button.  A 33-year-old woman complained of pain and swelling in her belly button for the past 2 years, it got worse during her periods.  She had no prior history of pelvic or abdominal surgeries.  She received an ultrasound as well as a fine needle aspiration cytology.  The ultrasound showed a lesion and pathology results of the FNAC suggested umbilical endometriosis.   A laparoscopy was done to search for any pelvic Endometriosis.  None other was found.  The belly button lesion was removed and sent off to pathology.  The umbilical Endometriosis suspicion was confirmed.  Her next period yielded no problems.

A 2019 abstract discussed a 42-year-old woman who had no prior surgical history. She presented with a weird nodule (skin-colored) on the left side of her torso near her inguinal area. The nodule was tender, but she had no other symptoms. It was removed and tested, and found to be Endometriosis – just developed out of the blue with very little to no symptoms. The abstract doesn’t state if they were going to pursue any sort of exploratory surgery to search for other Endometriosis within her body.

Another 2019 study in the International Journal of Women’s Dermatology was of a 41-year-old woman who had a painful lump in her belly button for 5 months. The pain flared up during her period. Her medical history included a 2009 miscarriage as well as a 2012 surgery that removed her left fallopian tube due to an ectopic pregnancy. She had been undergoing treatments for her infertility. A punch biopsy confirmed it was cutaneous Endometriosis, but she put off hormonal therapy since she was trying to get pregnant. She received a referral for excision surgery. They theorize the endometriosis cells were transferred to her belly button during her 2012 surgery. The study continues to outline several cases of cutaneous Endometriosis and states that only 1% of endometriosis cases involve the skin.

The International Society for Gynecologic Endoscopy published a November 2020 study of a 40-year-old woman who had a painful lump in her naval that bled when she was on her period. It started about 8 months prior, the pain and bleeding would routinely start two days before her period (and bleed for the duration), and her belly button would swell during that time. She’d never had any abdominal surgeries in the past. The lump was approximately 1.5 inches wide. An ultrasound showed the mass extended about an inch beneath her belly button. It was surgically removed and she didn’t have any symptoms six months later, although she was warned that recurrence could happen. Pathology confirmed it was cutaneous Endometriosis.

A December 2020 study in Hindawi discussed a 45-year-old woman who went to the hospital because of a painful lump in her belly button. It measured a little smaller than half-an-inch by half-an-inch. She had no prior surgical history, but was able to birth two kiddos. And the pain of the little below-the-skin belly button bump worsened on her periods over the past several years. Upon physical examination, the lump felt hard beneath the skin. An ultrasound showed the solid mass did not perforate into the pelvic cavity and rested between the skin and fascia. It was surgically removed (using local anesthesia) and once the skin was removed from the area, the nodule was visualized and was reddish-brown in color. Pathology confirmed it was umbilical endometriosis (a Villar’s Nodule). The patient did not receive any sort of medical treatment after the surgery and five years later remained symptom-free. [A rant from yours truly: The opening sentence of the Case Study references “A good looking 45-year-old woman…” and later discusses “aesthetic and psychological factors associated with total excision of the umbilicus, given its importance regarding sexuality.” They continue to discuss (for another paragraph) the history and significance of “the seductive power” of the umbilicus. Just the fact that the authors of the study found it necessary to 1) judge the patient’s appearance [and note it in the study] and 2) sexualize the belly button’s appearance really chaps my hide! I understand the personal importance that aesthetic and body image may hold for each patient, but this comes across as extremely objectifying and derogatory in this article. *shakes fist in the air*]

The Indian Journal of Dermatology, Venereology and Leprology published a study in February of 2021 of a 29-year-old woman who had a dark mass develop in her belly button a year prior. It was painful during her period. It felt very firm and a CT scan showed it increased in density in the umbilical area, but did not extend to any organs. A biopsy showed it was umbilical Endometriosis. Once they received the biopsy results, a surgery was performed to remove the entire mass. There is an incredible picture of her belly button Endo in the study!

In April 2021, Cureus published a study of a 28-year-old female who had previously undergone a surgery to remove her gallbladder. She had no prior history of Endometriosis symptoms. One day she developed a small bumps inside of her belly button that grew and bled (only during her menstrual cycle) over the past year (since her gallbladder surgery). She had no other signs or symptoms of Endometriosis. The bumps were skin-colored lesions. CT scans were performed and she was referred to a general surgeon to remove what they suspected to be Endometriosis. Their suspicions were confirmed with a biopsy: umbilical Endometriosis. It’s theorized that perhaps some sort of cell transplant occurred during her surgery from a year prior, but she still had no prior (nor later) symptoms of Endometriosis.

One study summed up what any Endo suffer already knows:

“Education of all doctors, including the primary care physicians, is important to help early diagnosis and treatment of this agonising condition.” ~Cutaneous Endometriosis; A. Agarwal, Y.F. Fong

What did I learn from all of this?  So much!!  But most importantly?  Pay attention to your body.  If something doesn’t look or feel right, don’t be afraid to ask your doctor.  And if you’re bleeding out of a weird spot during your periods, dude…seriously…have your doctors check it out!

Do you, or someone you know, have skin Endometriosis?  I’m so fascinated (and terrified), I’d love to hear the story! Drop a comment below…

And for OTHER areas of the skin that Endo has been found, please check out these blog entries:

Butt crack

Cleavage

Tear duct

*Updated September 27, 2021*

Resources:

Acta Dermato Venereologica : Article (2007) Diagnosis and Treatment of Post-caesarean Scar Endometriosis

Acta Dermato Venereologica : Article (2009) Spontaneous Endometriosis in an Umbilical Skin Lesion

Cureus : Article (2021) Umbilical Endometriosis Following Laparoscopic Cholecystectomy

Deep Dyve : Article (2010) Cutaneous Endometriosis : A Review of 15 Cases Diagnosed at a Single Institution

Dermitol Sinica : Article (1995) Cutaneous Endometriosis of the Umbilicus

EC Gynaecology : Article (2017) Extra-Gonadal Endometriosis with Unusual Presentation: A Case Report

Gallica

Case Reports in Surgery: Article (2020) Primary Subcutaneous Umbilical Endometriosis: Case Report and Review of the Literature

Indian Journal of Dermatology, Venereology and Leprology: Abstract (2021) Primary Cutaneous Endometriosis of the Umbilicus

Indian Obstetrics & Gynaecology: Article (2018) Primary Umbilical Endometriosis: A Case Report  

International Journal of Women’s Dermatology: Article (2019) Cutaneous Endometriosis

Journal of Clinical and Diagnostic Research : Article (2015) Spontaneous Fingertip Endometriosis : A Rare Case Report

Journal of Endometriosis and Pelvic Pain Disorders : Abstract (2011) A Case of Cutaneous Endometriosis Following Vulvar Injury

Journal of Rare Disorders: Diagnosis and Therapy : Article (2017) Spontaneous Cutaneous Endometriosis of Umbilicus: A Case Report

Keio University : Abstract (2016) Abdominal Wall Endometriosis that Developed at the Port Site After Laparoscopic Cholecystectomy

Papersearch : Abstract (2019) A Case of Primary Inguinal Endometriosis Without Previous Surgical History

Royal Australasian College of Surgeons : Article (2017) Umbilical Endometriosis: A Potential Encounter for General Surgeons

Singapore Medical Journal : Article (2008) Cutaneous Endometriosis

Diseases of the Colon & Rectum : Abstract (1967) Endometriosis of the Anal Canal : Presentation of a Case

The International Society for Gynecologic Endoscopy : Article (2020) Primary Umbilical Endometriosis with Menstruation from the Umbilicus : A Case Report and Review of the Literature

Acta Dermatovenerologica Alpina: Abstract (2009) Spontaneous Endometriosis in an Umbilical Skin Lesion

Clinical and Experimental Obstetrics & Gynecology : Abstract (2009) Spontaneous Umbilicus Endometriosis : a Case Report with One-year Follow-up.

Annales de Dermatologie et de Venereologie: Abstract (2017) Umbilical Endometriosis Mimicking a Keloid in a Young Black Woman: A Case Report

~ Again, I am a layman.  I do not hold any college degrees, nor mastery of knowledge.  Please take what I say with a grain of salt.  If curious, do your own research 😉 Validate my writings.  Or challenge them.  And ALWAYS feel free to consult with your physician. Always.  Yours ~ Lisa