Uterine metastasis is a rare condition that usually presents as part of widespread metastatic disease. Most common primary tumors are breast carcinoma, ovarian carcinoma, colorectal carcinoma, gastric carcinoma, and cervical carcinoma. Metastasis occurs via hematogenous route (most common), lymphatic spread, or direct extension (ovary, cervix). Presents as focal or multiple solid mass(es) in the myometrium. On imaging, myometrial mass shows DWI restriction, heterogeneous enhancement, and rapid growth. Endometrium is typically preserved (different from primary endometrial carcinoma). Clinically, abnormal uterine bleeding, pelvic pain, or incidental detection occurs. Prognosis is generally poor because uterine metastasis indicates widespread disease. Presence of known primary malignancy and multiorgan involvement are important diagnostic clues.
Age Range
40-80
Peak Age
60
Gender
Female predominant
Prevalence
Rare
Uterine metastasis occurs through three routes: (1) Hematogenous spread — the most common route. Reaches the myometrium from primary tumors such as breast, gastric, and melanoma via arterial or retrograde venous route. Rich vascularization of uterine arteries facilitates hematogenous metastasis. (2) Lymphatic spread — from cervical and ovarian tumors via retrograde lymphatic route through pelvic lymph nodes. (3) Direct extension — from adjacent organ tumors (ovary, cervix, colorectal) via peritoneal or direct invasion. Metastatic cells settle in the myometrium and grow by establishing neovascularity. Intratumoral necrosis is common due to rapid proliferation and insufficient vascular support → heterogeneous imaging findings. Diffusion restriction on DWI results from high cellularity — metastatic cells show dense nuclear-to-cytoplasmic ratio and tight cell packing → free water molecule movement is restricted → low ADC. Enhancement patterns reflect vascular characteristics of the primary tumor — hypervascular metastases (RCC, melanoma) show prominent enhancement, hypovascular metastases (breast, colorectal) less enhancement.
The most important distinguishing finding of uterine metastasis is the presence of myometrial mass within the myometrium without endometrial invasion. In primary endometrial carcinoma, tumor originates from the endometrium and invades the myometrium — the endometrium-myometrium interface is disrupted. In metastasis, the tumor reaches the myometrium via hematogenous route → endometrium is generally preserved and of normal thickness. This finding is best evaluated on T2-weighted sagittal MRI images.
On DWI, myometrial metastasis demonstrates prominent diffusion restriction. Hyperintense signal on high b-value images (b=800-1000) and low signal on ADC maps are observed. ADC values are generally <1.0 × 10⁻³ mm²/s, reflecting high cellularity. Diffusion restriction may vary with primary tumor type but is generally prominent. Detection of diffusion restriction in all lesions of multiple masses supports metastatic disease. This finding is valuable in distinguishing from benign leiomyoma — leiomyoma without degeneration generally does not show significant diffusion restriction.
Report Sentence
Solid mass(es) in the myometrium demonstrating prominent diffusion restriction and low ADC values on DWI; consistent with metastasis in the context of known primary malignancy.
On T2-weighted MRI, uterine metastasis generally shows intermediate-to-hyperintense signal — different from homogeneous T2 hypointense signal of typical leiomyoma. T2 signal intensity varies with primary tumor type: breast carcinoma metastasis generally T2 hypointense-isointense, ovarian carcinoma metastasis T2 hyperintense (may have cystic component), melanoma metastasis T2 hypointense (due to melanin content). Endometrium is generally preserved and normal thickness — this finding is the most important distinguishing clue from primary endometrial carcinoma.
Report Sentence
Solid mass with intermediate-to-hyperintense signal on T2-weighted sequences in the myometrium with preserved endometrium; metastasis should be considered in the context of known primary malignancy.
On contrast-enhanced MRI, uterine metastasis demonstrates heterogeneous enhancement. Enhancement pattern depends on primary tumor type — metastases from hypervascular tumors (RCC, melanoma, thyroid) show prominent and early enhancement, while metastases from hypovascular tumors (breast, colorectal) show less enhancement. Necrotic areas remain non-enhancing. Enhancement pattern differs from surrounding myometrium — normal myometrium enhances homogeneously and progressively. Ring-pattern enhancement (peripheral enhancement + central necrosis) is typical for metastasis.
Report Sentence
Solid mass in the myometrium demonstrating heterogeneous enhancement on contrast-enhanced MRI with accompanying central necrotic areas; consistent with metastasis in the context of known primary malignancy.
On contrast-enhanced CT, enhancing solid mass in the myometrium is observed. CT provides less information than MRI for uterine metastasis diagnosis but plays a critical role in pelvic/abdominal/thoracic staging and concurrent metastasis screening. Multiple masses, peritoneal implants, lymphadenopathy, and distant organ metastases are evaluated. Density of the myometrial mass varies with primary tumor type. Calcification may be seen in mucinous tumor metastases. Ovarian-origin metastases may be accompanied by bilateral ovarian masses + ascites + peritoneal implants.
Report Sentence
Enhancing solid mass in the myometrium on contrast-enhanced CT; concurrent screening for other organ metastases and lymphadenopathy is being performed.
On B-mode US, uterine metastasis generally appears as hypoechoic or mixed echogenicity solid mass in the myometrium. Unlike leiomyoma, posterior shadowing is generally absent and borders may be more irregular. Multiple lesions support metastatic disease. Increased and irregular vascularity may be detected on Doppler. US is used for initial evaluation but MRI is required for characterization. Normal endometrial thickness argues against primary endometrial carcinoma.
Report Sentence
Hypoechoic solid mass in the myometrium with irregular borders and absence of posterior shadowing differing from typical leiomyoma; metastasis should be considered in presence of known primary malignancy.
Criteria
Most common primary source. Spreads hematogenously. Lobular carcinoma generally metastasizes to myometrium more frequently.
Distinct Features
Generally T2 hypointense-isointense (fibrous stroma) on T2. DWI restriction prominent. May frequently show diffuse infiltration pattern. Interaction between hormone receptor positivity and uterine myoma treatment is important.
Criteria
Via direct extension or peritoneal spread. Accompanied by bilateral ovarian masses + ascites + peritoneal implants.
Distinct Features
Generally T2 hyperintense (cystic-solid component). Evaluation of serous cavity important — implants in Douglas. CA-125 elevated.
Criteria
Direct extension (rectum) or hematogenous/lymphatic spread. Frequently direct invasion from rectosigmoid tumors.
Distinct Features
Mucinous component may show low density on CT. Calcification in mucinous types. CEA elevated. Invasion pattern from uterine serosal surface may be observed.
Distinguishing Feature
Leiomyoma shows homogeneous hypointense signal on T2, no significant DWI restriction, and has well-defined pseudocapsule. Metastasis shows higher T2 signal, prominent DWI restriction, and irregular borders. Rapid growth is not expected in leiomyoma.
Distinguishing Feature
Leiomyosarcoma is a primary uterine tumor and generally appears as solitary large mass. Metastasis is frequently multiple and appears in the context of known primary malignancy. Endometrium may be preserved in both, but more prominent necrosis and heterogeneity are expected in leiomyosarcoma. Definitive distinction is made with clinical context and biopsy.
Distinguishing Feature
Endometrial carcinoma originates from endometrium → endometrial thickening and intracavitary mass observed. Myometrial invasion spreads from endometrium toward myometrium. In metastasis, mass is within the myometrium and endometrium is generally preserved — this is the most important distinguishing finding.
Urgency
urgentManagement
medicalBiopsy
NeededFollow-up
specialist-referralUterine metastasis is generally part of widespread metastatic disease, and treatment is determined by the type and stage of the primary tumor. Biopsy may be needed for histological confirmation — especially if the primary tumor is unknown or detected after a long disease-free interval. Treatment is generally systemic chemotherapy and/or hormonal therapy (breast metastasis). Palliative surgery or radiotherapy may be applied in symptomatic cases. Prognosis is generally poor — uterine metastasis reflects advanced-stage disease. Referral to oncology is mandatory. Follow-up is per the primary tumor protocol.
Uterine metastasis indicates advanced-stage disease. Treatment is planned according to the primary tumor and overall disease spread. Biopsy may be needed for primary/metastatic differentiation. Prognosis is generally poor and depends on primary tumor histology.