Small cell carcinoma of endometrium

Clinical History

Patient had recently developed a painful enlarging left mandibular swelling and facial numbness. Maxillo-facial team requested a CT examination to assist with the diagnosis. There was a known six-month history of intermittent vaginal bleeding and generalised aches and pains. It was initially uncertain if these two presenting complaints were related.

Imaging Findings

MRI PELVIS: The endometrium measure is thickened and segments show poor demarcation with the junctional zone indicating deep myometrial invasion. The entire uterus appears infiltrated, resulting in an abnormally enlarged uterus with intermediate signal intensity on T2. Small cell cancer of the endometrium or endometrial lymphoma was suspected at this stage.

Bilateral external iliac lymphadenopathy are present. Patchy moth-eaten infiltrative appearances in the imaged skeleton suggests widespread skeletal metastases.

MANDIBLE CT: Metastatic destruction of the left body of mandible due to biopsy proven small cell endometrial carcinoma. There was widespread skeletal metastatic deposits.

PET SCAN: Intense FDG uptake in the known primary small cell endometrial carcinoma with extensive FDG avid skeletal metastatic deposits and widespread hypermetabolic intra-abdominal and pelvic lymphadenopathy. Local disease extent is best appreciated on the MRI scan. Left Mandibular lesion is considered part of the secondary disease.

Discussion

Primary small cell carcinoma of the Endometrium is a rare aggressive carcinoma of endometrial origin resembling small cell carcinoma of the lung. This tumour may exhibit evidence of neuroendocrine differentiation and has a high propensity for systemic spread, a poor prognosis and rarely paraneoplastic syndromes [1].

Clinically endometrial cancer presents with abnormal vaginal bleeding or pain related to the primary tumour or metastasis. Non primary cases may originate in cervix and extend to the uterine corpus. Mean age 60 years, range 23-78 years. Incidence is <1% of endometrial carcinomas with around 60 cases reported in literature. It is associated with endometrioid adenocarcinoma, adenosquamous carcinomas, mixed mullerian tumours and endometrial stromal sarcomas in some cases, but pure tumours are also reported [1].

On MRI imaging endometrial carcinoma generally manifests as hypo- to isointense on T1-weighted images and hyperintense or heterogeneous on T2-weighted images. Although MR imaging is not helpful in differentiating endometrial carcinoma from hyperplasia, it is helpful in cancer staging. Tumours are staged on the basis of depth of myometrial invasion. T1-weighted gadolinium-enhanced MR imaging is helpful in demonstrating myometrial invasion because a carcinoma will enhance less than normal endometrium [2].

Superficial invasion involves only the inner half of the myometrium, whereas deep invasion involves the outer half of the myometrium and beyond. If the normal low-signal-intensity junctional zone is intact, myometrial invasion can most likely be excluded. If the junctional zone is thinned due to atrophy or distention from clot, fluid, or polypoid tumour and is not well visualized, the presence of myometrial invasion is indicated by loss of the normal endometrium-myometrium interface. An irregular interface suggests invasion [3]. Both MR imaging, CT and in this case PET CT are useful in demonstrating extrauterine spread and lymphadenopathy.

Treatment involves total abdominal hysterectomy, bilateral salpingo-oophorectomy and pelvic and paraaortic lymph node dissection, followed by radiation therapy and chemotherapy [1]. There are few cases reported each year to have a clear consensus regarding best treatment but in most cases it is quite aggressive and shows early metastatic spread.

Clearly prompt clinical diagnosis followed with radiological imaging and access to prompt oncology services is of paramount importance.

Differential Diagnosis List

Final Diagnosis

Small Cell Carcinoma of Endometrium with squamous differentiation

URL:	https://www.eurorad.org/case/10322
DOI:	10.1594/EURORAD/CASE.10322
ISSN:	1563-4086