Pedunculated Adenomyoma with Osseous Metaplasia: A Case Report

Our case involves a 40-year-old single female patient who sought medical assistance due to chronic lower abdominal pain persisting for 1 year prior to her first gynecological evaluation. Upon presentation, she reported experiencing colicky right lower quadrant abdominal pain, partially relieved by simple analgesia. This pain was occasionally accompanied by nausea, bloating, and constipation. The patient has a medical history of familial Mediterranean fever, type 2 diabetes mellitus, and iatrogenic hypothyroidism. She reports regular menstrual cycles and denies abnormal uterine bleeding, unusual vaginal discharge, or constitutional symptoms. Additionally, she is not sexually active. During the outpatient evaluation, abdominal tenderness on the right side was noted, and a bedside ultrasound revealed a large right adnexal cyst with mixed echogenicity. Blood tests, including tumor markers, were within normal limits. Pelvic magnetic resonance imaging (MRI) showed a space-occupying lesion measuring 8.4 cm × 5.7 cm on the right side of the pelvis, exerting mass effect on the uterus and displacing it to the left [ Figure 1 ]. The mass appeared mainly isointense with hyperintense contents. However, the uterus and other adnexa appeared normal. These findings strongly suggested a right ovarian mass, likely a dermoid or epidermoid tumor, for which the patient was scheduled for laparoscopic cystectomy. Magnetic resonance imaging axial section showing a right adnexal lesion with a combination of soft tissues and fat causing pressure effect on the uterus (arrow) During laparoscopy, a large pedunculated uterine myoma was discovered on the right postero-fundal aspect of the uterus [ Figure 2 ], initially thought to be the right adnexal cyst seen on radiological imaging. Laparoscopic myomectomy was successfully performed, and calcified tissues were noted during manual morcellation. Samples were retrieved and sent for histopathological examination. Laparoscopic view showing a large pedunculated uterine tumor (arrow) on the right posterior-fundal aspect of the uterus (u), which was initially thought to be the right adnexal cyst seen on magnetic resonance imaging Histopathological evaluation confirmed the diagnosis of adenomyoma with extensive calcification and focal osseous metaplasia [ Figure 3a and b ]. (a) Several benign endometrial glands are present, surrounded by a spindly endometrial stroma within the myometrium. Some of the glands appear cystically dilated. The findings here align with adenomyoma. (b) This image demonstrates myometrial tissue with extensive calcification and osseous metaplasia. Deposits of refractile crystalline material (likely oxalate crystals) are visible in the tissue. These findings further support adenomyoma with significant calcification and ossification changes

Adenomyosis is a gynecologic condition characterized by ectopic endometrial tissue within the uterine myometrium. It commonly occurs in multiparous women in their late childbearing age which can cause significant morbidity and may adversely impact daily activities.[ 1 ] Adenomyosis can be diffuse, focal, or polypoid. They further classified focal into adenomyoma and cystic adenomyosis, polypoid into typical and atypical depending on the presence or absence of cellular atypia, and others including endocervical and retroperitoneal.[ 2 ] Most women with adenomyosis are asymptomatic. However, Symptoms associated with adenomyosis are abnormal uterine bleeding and pelvic pain which might be in the form of dysmenorrhea, dyspareunia, or chronic pelvic pain. Furthermore, adenomyosis can contribute to fertility impairment and adverse pregnancy outcomes.[ 3 ] Osseous metaplasia is a pathological condition where it is characterized by the replacement of normal epithelium into osteoblastic cells that produce bone.[ 4 ] Osseous metaplasia can occur in the cervix or the endometrium with many reported cases in the literature mentioning the previously remarked sites.[ 4 ] However, no reported cases revealed the presence of osseous metaplasia in adenomyoma.

The term “uterine adenomyoma” was initially described in 1896.[ 5 ] However, the first comprehensive description of these tumors was published in 1918.[ 6 ] Only a small number of references and limited discussion of adenomyomas can be found in contemporary literature.[ 5 ] The most common manifestation of adenomyoma is a polypoid lesion extending into the endometrial cavity.[ 7 ] Although less prevalent, adenomyoma can also present as a myometrial or subserosal mass in the uterine corpus.[ 8 ] Adenomyomas’ histogenesis is not thoroughly understood, and it is still unclear if these growths are neoplasms or a confined form of adenomyosis.[ 5 ] It has been widely recognized that the process of adenomyosis begins with the basalis endometrium invaginating the myometrium or what is known as the intrinsic variety. Nonetheless, with an abundance of MRI data, a new theory has now been proposed. This theory suggests there may be an extrinsic form of adenomyosis that develops from an invasion of pelvic endometriotic lesions into the uterus disrupting the uterine serosa.[ 9 ] The characteristics of extrinsic adenomyosis include the maintenance of healthy muscular tissues between the adenomyosis and the junctional zone, as well as an intact junctional zone. This type mostly occurs in the posterior uterine wall and is frequently associated with pelvic endometriosis.[ 10 ] The absence of apparent pelvic endometriosis in our case raises the question of whether internal or extrinsic mechanisms may have contributed to the formation of the pedunculated adenomyoma. Moreover, MRI scans revealed a space-occupying isointense right pelvic mass with hyperintense components, indicating fatty content, which was suppressed in diffusion-weighted imaging. Additionally, hypointense regions in all sequences indicated the presence of calcifications, but necrotic tissue is less likely. These features strongly indicated a right ovarian mass, most likely a dermoid or epidermoid tumor [ Figure 1 ]. The intraoperative finding revealed a large pedunculated uterine myoma on the right postero-fundal aspect of the uterus [ Figure 2 ] which was thought to be the right adnexal cyst according to the MRI findings. On the other hand, the postoperative pathology report revealed myometrial tissue with smooth muscle fibers and no pathological atypia, as well as numerous benign endometrial glands surrounded by thin endometrial stroma within the myometrium. There was no indication of malignancy [ Figure 3a ]. Multiple areas showed considerable calcification and transition into bone tissue. In other regions, deposits of refractile crystalline material, most likely oxalate crystals, have also been detected. These findings suggest adenomyoma with calcification and osseous metaplasia [ Figure 3b ]. Osseous metaplasia is a rare cytomorphological transformation that was reported primarily in the endometrium in which the normal endometrial phenotype of uterine epithelial cells is replaced with bone-type mesenchymal components.[ 11 ] To explain metaplasia’s origin, several pathogenetic theories have been proposed: 1 – the transformation of multipotential stromal cells; 2 – persistent endometrial estrogen stimulation; 3 – hypotrophic calcification of retained and necrotic tissues after one or more abortions; 4 – metabolic disorders such as hyperphosphatemia, hypercalcemia, or hypervitaminosis D.[ 11 ] Furthermore, Osseous metaplasia has also been reported in the cervix, ovary, vagina, and mesosalpinx.[ 12 ] There have been limited reports of anomalous adenomyoma cases in literature. Massive cyst growth was observed in a polypoid adenomyoma,[ 8 ] and mature adipocytes were found in an otherwise normal adenomyoma and designated as adenomyolipoma.[ 13 ] A tumor exhibiting skeletal muscle differentiation was also reported as an additional instance of heterologous differentiation within an adenomyoma.[ 14 ] In the present case, the preoperative diagnosis was suggested to be a dermoid cyst according to the MRI findings due to the similarities in MRI features. Adenomyomas are rare benign uterine tumors that are often misdiagnosed. While this case helps broaden the differential diagnosis for calcified uterine tumors recognized on MRI to include adenomyomas, it is important to recognize that MRI does not necessarily help with the distinction between dermoid cysts and calcified adenomyoma. The final differentiation and diagnosis will ultimately lie with the pathologist. The study was conducted in accordance with the Declaration of Helsinki and was approved by Istishari Hospital IRB Committee with (approval number: Number: IRBIH/ IAA/2.3.24 ). Patient consent form was obtained from the patient. Conceptualization : Luay Abu Atileh, Nouf Khalifeh, Caroline Sabanekh, Lina Amairi, and Bayan Al Omari; investigation: Luay Abu Atileh, Nouf Khalifeh, Caroline Sabanekh, Lina Amairi, and Bayan Al Omari; resources: Luay Abu Atileh, Nouf Khalifeh, Caroline Sabanekh, Lina Amairi, and Bayan Al Omari; Writing – original draft preparation: Luay Abu Atileh, Nouf Khalifeh, Caroline Sabanekh, Lina Amairi, and Bayan Al Omari; writing – review and editing: Luay Abu Atileh, Nouf Khalifeh, Supervision, and Luay Abu Atileh. All authors have read and agreed to the final version of the manuscript.” Data sharing not applicable to this article as no datasets were generated or analyzed during the current study. There are no conflicts of interest.