accessory and cavitated uterine mass ( acum ) is a rare , newly recognized mullerian anomaly .
it is an accessory cavity lined by functional endometrium within an otherwise normal uterine cavity , in contrast to the other mullerian anomalies in which the uterus is malformed . the cavitated mass is locally defined to myometrium ( unlike diffuse adenomyosis )
, is encapsulated ( unlike myoma ) , and bears uterus - like histological organization ( unlike adenomyoma ) .
the entity needs expertise to diagnose as it is a rare but treatable cause of severe dysmenorrhea and chronic pelvic pain in young females with a wide range of differential diagnosis .
a 24-year - old unmarried female presented with severe dysmenorrhea and chronic pelvic pain since menarche , which aggravated 2 years prior to presentation .
she was treated with non - steroidal anti - inflammatory drugs ( nsaids ) earlier and with oral contraceptive pills ( ocp ) for the last few months .
previous serial usg reports revealed a 3.0  3.6 cm , solid right adnexal mass abutting the right ovary with likely ovarian origin . on repeat usg pelvis , a homogeneous isoechoic
well - defined mass was noted in the right adnexa between uterus and right ovary , with central echogenicity [ figure 1 ] .
uterus and bilateral ovaries appeared normal and there was no fluid in pouch of douglas .
a differential diagnosis of rudimentary horn with unicornuate uterus was considered . on usg upper abdomen , multiple non - obstructing right renal calculi and gall bladder ( gb ) calculi were noted .
serum calcium , phosphate , parathyroid hormone ( pth ) , uric acid , liver and renal function tests , urine analysis , and urine calcium were within normal limits .
usg pelvis transverse images showing well - defined isoechoic uterus like mass with central echogenic endometrium in the right adnexa .
the uterus appeared normal with a well - defined , rounded , non - communicating cavitated mass measuring 3  4 cm noted along the right anterior uterine wall just below the insertion of round ligament .
the cavity was lined by t2-hyperintense endometrium with hemorrhagic contents within , which appeared hyperintense on t1 and hypointense on t2w images [ figure 2 ] .
the junctional zone of the cavity was thickened ( 13 mm ) and endo - myometrial interface was indistinct .
the main uterine cavity was normal in shape and size , and both the cornua were visualized normally [ figure 3 ] which ruled out usg diagnosis of rudimentary horn .
the junctional zone , endomyometrial interface , and myometrial signal intensity of the main uterine cavity were normal .
no pelvic endometriotic deposits were seen and there was no evidence of hematosalpinx . based on the above findings , a diagnosis of acum was considered .
( a ) axial t1w , ( b ) fat - saturated axial t2w , and ( c ) coronal t2w images showing a cavitated mass attached just below the round ligament containing t1-hyper and t2-hypointense contents suggestive of blood products ( a and b ) and lined with t2-hyperintense endometrium ( c ) . the junctional zone is thickened with ill - defined endo - myometrial interface ( curved arrow ) .
note thin ( 4 mm ) junctional zone with sharp endo - myometrial interface ( straight arrow ) in normal uterine cavity , u axial fs t2w images ( a - c ) and coronal t2w images ( d - f ) showing normal - shaped uterine cavity with both cornua ( arrows ) attached normally .
bilateral ovaries ( * ) are seen separate from the mass , m as hsg is best avoided in young unmarried patients , laparoscopy was done .
on laparoscopy , the mass was found to be attached to the right anterior uterine wall just below the attachment of right round ligament .
a transverse incision was made over the anterior wall of the mass and 10 - 12 ml of chocolate - colored fluid was drained .
histopathology revealed a cavitated mass lined by functional endometrium with glands and stroma surrounded by irregularly arranged smooth muscle cells .
foci of adenomyosis were also noted within the myometrium of the mass [ figure 4 ] .
the smooth muscle cells stained positive for desmin , estrogen receptor ( er ) , and progesterone receptor ( pr ) .
photomicrograph ( a ) showing functional endometrium e , with glands and stroma lining the cavity wall and surrounded by irregularly arranged smooth muscle cells m , resembling myometrium .
foci of adenomyosis ( b ) are seen within the myometrium of the resected specimen ( arrow )
american society of reproductive medicine classification of mullerian anomalies uterus - like mass ( ulm ) is an uncommon distinct entity described in literature which represents cavitated mass lined by endometrial glands and stroma that are surrounded by irregularly arranged smooth muscle cells , which in addition to other smooth muscle markers also show positivity for er and pr , resembling myometrium .
hence , these ulms bear both macroscopic and microscopic resemblance to the uterus and can arise anywhere within and beyond the uterus at any age .
the entity needs to be classified separately as the uterine cavity is otherwise normal unlike other mullerian anomalies .
it characteristically presents at a younger age , usually < 30 years , with severe dysmenorrhea and chronic pelvic pain due to distention of the cavity caused by repeated bleeding .
various authors have previously described such masses with different names such as juvenile cystic adenomyoma ( jca ) , cavitated adenomyoma , accessory cavitated masses , etc .
the condition is separate from cystic adenomyosis which is seen in middle - aged females due to diffusely spread adenomyotic foci in the uterus .
the cysts are typically small , usually less than 5 mm , due to periodic hemorrhage in ectopic endometrium , and on histopathologic examination ( hpe ) , they lack typical endometrial lining and uterus - like smooth muscle organization .
acum , on the other hand , is seen in adolescents and resembles uterus on microscopy .
the main uterine cavity and myometrium is otherwise normal ; however , myometrium of acum itself may develop adenomyosis due to increased intracystic pressure .
there are three theories of development : ( 1 ) congenital anomaly theory , ( 2 ) heterotopias theory , and ( 3 ) metaplasia theory .
the proposed mechanism says that the accessory mass could be caused by duplication of ductal mullerian tissue in the critical area at the level of attachment of round ligament , possibly related to gubernaculum dysfunction .
the first case of ulm was reported by cozzutto in 1981 . around 36 cases of acum
have been reported in literature with various terminologies , of which 22 have been reported after 2010 probably due to increased awareness . beginning from 2010 , the greatest number of cases ( n = 9 ) has been reported by takeuchi et al . , although they limited the inclusion criteria to women under 30 years of age .
reported four cases in 2011 , and one case each was reported by akar et al . in 2010 and chun et al . in 2011
in 2012 , jain reported two cases of jca , simulating mullerian anomalies . in 2013 , another case with its laparoscopic management has been reported by bedaiwy et al .
the most common extrauterine site is ovary ; however , such masses have been seen in broad ligament , small bowel , mesentery , appendix , colon , conus medullaris , and utero - sacral ligament .
the criteria for diagnosing acum are : ( 1 ) an isolated accessory cavitated mass usually located under round ligament ; ( 2 ) normal uterus , fallopian tubes , and ovaries ; ( 3 ) a surgical case with excised mass and pathological examination ; ( 4 ) an accessory cavity lined by endometrial epithelium with glands and stroma ; ( 5 ) chocolate brown colored fluid contents ; ( 6 ) no adenomyosis in the uterus ( if resected ) , although there could be tiny foci of adenomyosis in the myometrium of the accessory cavity due to increased intracystic pressure .
although most of the cases fulfill all the above mentioned criteria , there have been few exceptions .
there was one case showing two acum in the same patient , one case of acum in a patient with co - existing other mullerian anomaly and one with accessory rudimentary tube attached with the mass .
usg is the initial imaging modality that can identify them as solid isoechoic to predominantly cystic masses resembling endometrioma arising within the uterus , visualized separately from the ovaries .
however , the most important role of hsg lies primarily in ruling out any mullerian anomaly .
mri is the imaging modality of choice as it non - invasive and , hence , preferred over hsg in young unmarried females .
it clearly shows the pelvic anatomy ; cavitated mass with hemorrhagic contents ; and the uterus , myometrium , and endo - myometrial interface .
thin sections ( 3 mm ) should be used as it will also help in ruling out mullerian anomaly by demonstrating both cornua clearly . in our case ,
visualization of normal size and shape of the uterus and both cornua ruled out mullerian anomalies .
cystic degeneration in adenomyoma and fibroid will not show t2-hyperintense endometrial lining and hemorrhagic contents and are not usually seen in adolescents .
the entity closely mimics obstructed cavitated rudimentary horn with unicornuate uterus and differentiation may be difficult .
hsg can be done to differentiate the two , but mri is the preferred non - invasive modality .
both of them show cavitated mass lined by endometrium with hemorrhagic contents within it , but contralateral tilt of the uterus , banana - shaped small uterine cavity , and a single cornua favors obstructed horn over acum which was not seen in our case .
however , at times , the differentiation may not be possible on mri and laparoscopy remains the only option available for confirmation and treatment .
to the best of our knowledge , except a few cases , most of the cases were misdiagnosed preoperatively as other mullerian anomalies , cystic degeneration in adenomyoma and leiomyoma , and broad ligament fibroids .
awareness and adequate knowledge of the entity can help the radiologist make accurate pre - operative diagnosis of acum .
acum , a rare mullerian anomaly related to dysfunction of gubernaculum , is a treatable cause of severe dysmenorrhea in young females .
the mri findings of an accessory cavitated ulm located below the attachment of round ligament usually with hemorrhagic contents , an otherwise normal - shaped uterus with both cornua identified normally , without any evidence of adenomyosis , and bilateral normal tubes and ovaries should suggest the diagnosis of acum pre - operatively .
 accessory and cavitated uterine mass ( acum ) is a rare form of developmental mullerian anomaly seen in young females , which presents as chronic recurrent pelvic pain and severe dysmenorrhea . 
 it is an accessory cavity lying within an otherwise normal uterus . 
 it is lined by functional endometrium and surrounded by myometrium - like smooth muscle cells ; hence , it bears striking macroscopic and microscopic resemblance to the uterus . 
 hysterosalpingography ( hsg ) , ultrasonography ( usg ) , and magnetic resonance imaging ( mri ) form the mainstay of diagnostic imaging . 
 the entity is often under diagnosed ; therefore , a high index of suspicion combined with hsg and mri imaging can help in making an accurate diagnosis . 
Introduction
Case Report
Discussion
Conclusion