a 23-year - old healthy female was admitted to our hospital with a new - onset tender bulge in her left groin , associated with subjective fevers and chills .
four days prior to presentation , she noted a sudden protrusion in her left groin with associated pain . given worsening pain and intermittent nausea , she presented to our emergency room . on admission , physical examination revealed a soft , non - distended abdomen that was tender to palpation in the left lower quadrant . a soft , mobile , exquisitely tender , and non - reducible mass
laboratory data were notable for a leukocyte count of 6.7 , a hematocrit of 36.9 and a lactate of 1.4 in the setting of normal electrolytes .
an outside ultrasound showed an avascular complex cystic lesion measuring 2.1 cm in the left groin .
a subsequent computed tomography scan of the abdomen and pelvis revealed a tubular cystic structure along the left inguinal canal , coursing along the expected path of the round ligament , without surrounding fat stranding or herniation of bowel loops .
given her symptoms and the unclear etiology of the hernia , she was admitted to the hospital and taken to the operating room for exploration ( fig .  1 ) .
in the operating room , a 6-cm dark purple cystic structure was visualized within the sac of an indirect inguinal hernia , travelling along the round ligament down toward the mons pubis ( fig .  2 ) .
the cystic structure was dissected away from the round ligament and the cyst was opened and noted to contain clear liquid .
ultimately , the patient underwent left indirect inguinal hernia repair , with gore bio a absorbable mesh , and excision of a left inguinal hydrocele of the round ligament .
final pathology revealed fibromuscular tissue lined by mesothelium consistent with a hernia sac and a hydrocele with concordant endometriosis .
the patient 's post - operative course was uneventful and she was discharged home on post - operative day 1 . 

figure  2:purple cystic structure within the sac of an indirect inguinal hernia , travelling along the round ligament down towards the mons pubis . left indirect inguinal hernia .
purple cystic structure within the sac of an indirect inguinal hernia , travelling along the round ligament down towards the mons pubis .
endometriosis is defined as the presence of ectopic endometrial glands and stroma at extrauterine sites .
it is a relatively common , benign , estrogen - dependent disorder that affects 10% of women of reproductive age .
it is characterized by chronic pain , severe dysmenorrhea and infertility , although the disease may be asymptomatic or discovered incidentally .
endometriosis can affect almost any organ system , although most ectopic implants are located in the pelvis .
extrapelvic endometriosis is a rare disease entity that may cause a variety of unusual symptoms , including pain and physiologic dysfunction , dependent on the location and size of lesions as well as the organ system affected .
it has been described at multiple sites including the gastrointestinal tract , urinary tract , thoracic cavity , central nervous system , umbilicus , skin ( including abdominal wall incisions and episiotomy scars ) and inguinal canal .
inguinal endometriosis is a condition characterized by the presence of endometrial stroma and glands in the extraperitoneal portion of the round ligament and in the surrounding connective and lymphatic tissues .
first described in 1986 , it is an extremely rare affliction with < 60 cases reported in the literature .
typically , patients are in their reproductive years , with a peak incidence between 3040 years , and present with tender inguinal swelling .
inguinal endometriosis is difficult to recognize and thus often confused with more common conditions such as hernias , lymphadenopathy , granulomas , soft tissue tumors , cysts and hydroceles .
catamenial symptoms , such as variation in size and tenderness of the mass , are present in 50% of cases and should raise the index of suspicion for inguinal endometriosis .
in many cases , the patient is brought to the operating room with a preoperative diagnosis of incarcerated hernia and the endometriosis is discovered incidentally or on histologic examination . in over 90% of cases , inguinal endometriosis occurs on the right side .
the endometriosis most often affects the extraperitoneal portion of the round ligament and is rarely found in association with occult hernias .
however , in a minority of cases , inguinal endometriosis can coincide with inguinal hernias and other groin pathology , increasing the diagnostic difficulty . in one series , 37% of patients suffered from inguinal endometriosis associated with a groin hernia .
the presence of isolated endometriosis contained within a left - sided inguinal hernia sac has , to our knowledge , never been reported . in all but two cases reported in the literature , or 91% of cases ,
the treatment of choice for both inguinal hernias and inguinal endometriosis is surgical excision . in order to be locally curative
, surgical excision must include the removal of the extraperitoneal portion of the round ligament .
given the high concordance of pelvic endometriosis , concurrent diagnostic laparoscopy or post - operative referral to a gynecologist is indicated to evaluate for other lesions and the extent of endometriosis . in some cases , there may be a role for hormonal suppression with oral contraceptives or gnrh agonists .
our patient underwent complete excision of a left inguinal hydrocele of the round ligament and repair of left indirect inguinal hernia with mesh .
she was started on hormonal therapy with an oral contraceptive and subsequently referred to a gynecologist for subsequent evaluation of her newly documented endometriosis .
all authors were members of the clinical team who saw the patient and treated the patient at the beth israel deaconess medical center .
the case report was written in large part by k.a . with contributions from all other authors .
 endometriosis is a common gynecologic disorder wherein ectopic endometrial glands and stroma are found at extrauterine sites . 
 extrapelvic endometriosis is a well - documented , yet rare , disease entity that can affect almost any organ system . 
 inguinal endometriosis is an extremely rare disease entity characterized by tender inguinal swelling . here 
 we report a case of a sudden - onset and acutely painful left inguinal hernia with concordant endometriosis . 
 a review of the literature is presented . 
 the presence of isolated endometriosis contained within a left - sided inguinal hernia sac has , to our knowledge , never been reported . 
 often diagnosed incidentally or on histologic examination , general surgeons should consider inguinal endometriosis in the differential diagnosis of inguinal masses , even in the absence of catamenial symptoms . 
 surgical excision , with gynecologic follow - up , is locally curative and the treatment of choice for inguinal endometriosis . 
CASE REPORT
DISCUSSION
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