Cecal leiomyoma mimicking a right adnexal mass: A rare diagnostic challenge

INTRODUCTION Adnexal masses are frequently encountered in reproductive-age women, yet their evaluation can be challenging when imaging features are nonspecific.[1] While ovarian fibromas are uncommon benign neoplasms,[2] gastrointestinal lesions such as cecal leiomyomas may radiologically mimic adnexal pathology and lead to misdiagnosis.[3,4] Cecal leiomyomas are exceptionally rare mesenchymal tumors originating from the bowel wall and are often asymptomatic. Only a few similar cases have been reported in the literature, highlighting the rarity of cecal leiomyomas and their potential to mimic adnexal pathology.[5] When large, they can present as pelvic masses and be mistaken for gynecologic tumors, particularly in women without gastrointestinal symptoms.[6] We report the case of a 34-year-old woman with a pelvic mass initially presumed to be of uterine or ovarian origin. Intraoperative findings revealed a benign cecal leiomyoma. This case highlights the diagnostic pitfalls of adnexal mass evaluation, emphasizing that nongynecologic tumors such as cecal leiomyoma may radiologically mimic adnexal lesions. It also underlines the importance of multidisciplinary assessment and awareness of imaging limitations in achieving an accurate diagnosis. CASE REPORT A 34-year-old woman (gravida 2, para 2) with no significant medical history or medication use presented with a 6-month history of chronic lower abdominal pain. Her surgical history included two previous cesarean sections. Pelvic examination revealed no adnexal or parametrial masses. However, transvaginal ultrasonography identified a well-circumscribed, solid-appearing mass measuring approximately 65 mm in the right adnexal region, with echotexture similar to the myometrium [Figure 1a]. The left ovary appeared normal, while the right ovary could not be clearly visualized due to the adjacent mass. Pelvic magnetic resonance imaging (MRI) demonstrated an 80 mm × 72 mm × 60 mm hypointense mass in the right adnexal region, showing internal degenerative changes and heterogeneous contrast enhancement, suggestive of a right ovarian origin [Figure 1b]. Written informed consent was obtained from the patient for publication of this case report and accompanying images. A Pfannenstiel incision was performed to access the abdominal cavity. Intraoperative exploration revealed no macroscopic abnormalities involving the uterus, ovaries, or fallopian tubes. However, a firm mass measuring approximately 8 cm was identified in the cecal wall, located posterior to the appendix and potentially extending toward the bowel lumen [Figure 2]. Intraoperative consultation with the surgical oncology team advised against immediate biopsy, recommending postoperative endoscopic evaluation. Following hemostasis, the abdomen was closed, and the procedure was concluded. Postoperative colonoscopy demonstrated external compression of the cecal lumen, with normal-appearing mucosa and no evidence of intraluminal lesions. Based on these findings, a right hemicolectomy was subsequently performed by the gastrointestinal surgery team. The patient recovered without complications and was discharged on postoperative day 5. The resected specimen was a well-circumscribed, firm, 8 cm submucosal lesion within the cecal wall. On gross examination, the cut surface was smooth, homogeneous, and pale tan, without hemorrhage, necrosis, or infiltrative growth. Microscopy revealed a sharply demarcated spindle cell tumor composed of intersecting fascicles. The cells had eosinophilic cytoplasm and elongated nuclei with bland chromatin and inconspicuous nucleoli. Immunohistochemistry showed diffuse strong cytoplasmic staining for H-caldesmon, confirming smooth muscle differentiation. Smooth muscle actin (SMA) and desmin showed weak but consistent positivity. The tumor was negative for CD117, DOG1, CD34, and S100, excluding gastrointestinal stromal tumor and neural tumors. Ki-67 index was low (1%–2%), indicating benign behavior. Although weak SMA and desmin expression may seem atypical for leiomyoma, this pattern is not uncommon in gastrointestinal smooth muscle tumors and may reflect a well-differentiated phenotype. The absence of atypia, mitotic activity, and necrosis ruled out leiomyosarcoma. Other mesenchymal tumors, such as inflammatory fibroid polyp, solitary fibrous tumor, and inflammatory myofibroblastic tumor, were excluded based on morphology and immunoprofile. No signs of syndromic or multifocal disease were observed. The histopathological and immunohistochemical characteristics of the tumor are shown in Figure 3.

Adnexal masses are frequently encountered in gynecologic practice and often require both imaging and physical examination for accurate diagnosis. Although transvaginal ultrasonography and pelvic MRI are informative, they may have limited accuracy when evaluating nongynecologic pelvic lesions that mimic adnexal pathology.[7] Cecal leiomyomas are rare benign tumors of smooth muscle origin that arise from the bowel wall and are infrequently reported in the literature.[4] These tumors are often asymptomatic and discovered incidentally. However, when large, they may mimic gynecologic neoplasms on imaging, especially in women without gastrointestinal symptoms.[5,6] In our case, radiologic findings suggested an ovarian or uterine origin, but pelvic examination did not reveal any abnormalities. This discrepancy led to intraoperative exploration, which revealed the true nature of the mass. The present case illustrates the limitations of relying solely on imaging findings and highlights the continued importance of physical examination, particularly in nonobese patients, where anatomical structures can be more clearly evaluated.[8] A careful bimanual examination can sometimes reveal discrepancies between radiologic impressions and actual pelvic anatomy. This emphasizes the irreplaceable value of clinical skills, even in the era of advanced imaging. Histopathological and immunohistochemical analyses were essential in reaching the final diagnosis. The tumor was diffusely positive for H-caldesmon, while staining for CD117, DOG1, CD34, and S100 was negative. These findings excluded gastrointestinal stromal tumors, neural tumors, and other mesenchymal neoplasms.[9,10] The absence of mitotic activity, cytologic atypia, and necrosis supported a benign diagnosis. While uterine and soft tissue leiomyomas are relatively common, cecal leiomyomas are exceptionally rare. These tumors may be misinterpreted as adnexal masses during imaging and are often identified during surgery for presumed gynecologic pathology. To our knowledge, only a few similar cases have been published. For example, Kho et al. reported a small bowel leiomyoma initially thought to be of gynecologic origin,[11] and Zuhdy et al. described an ascending colon leiomyoma that radiologically resembled a uterine fibroid.[12] Our case contributes to the limited literature by demonstrating that cecal leiomyomas can closely mimic adnexal tumors in both clinical and radiologic evaluations. Increased awareness of such presentations may help prevent misdiagnosis and guide appropriate surgical intervention. A multidisciplinary approach involving gynecology, gastrointestinal surgery, and pathology is essential in the management of complex pelvic masses. Previous reports of intestinal leiomyomas presenting as adnexal masses have described similar diagnostic challenges due to overlapping imaging features and the absence of gastrointestinal symptoms. However, in most published cases, the diagnosis was established intraoperatively or postoperatively, often after initial consideration of a gynecologic origin. Our case adds to the existing literature by emphasizing the radiologic–clinical discrepancy that may occur in such presentations and by highlighting the role of multidisciplinary assessment between gynecology, gastrointestinal surgery, and pathology in achieving an accurate diagnosis and avoiding unnecessary interventions.

This case demonstrates that imaging alone may not be sufficient to accurately identify the origin of pelvic masses. Clinical correlation through pelvic examination remains essential for diagnostic precision. Including rare gastrointestinal tumors such as cecal leiomyoma in the differential diagnosis can help avoid unnecessary gynecologic interventions and guide appropriate surgical planning through multidisciplinary collaboration. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given her consent for her images and other clinical information to be reported in the journal. The patient understands that name and initials will not be published and due efforts will be made to conceal identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.

Adnexal mass; cecal leiomyoma; diagnostic challenge