72 years old female patient complaining of hypogastric pain irradiating to the lower back region and recent constipation. Palpation of the right lower quadrant was painful but no mass was identified.
The patient was referred to our institution’s Gynecology Department with complaints of hypogastric pain irradiating to the lower back region and recent constipation. Her medical history showed
allergy to penicillin. On physical examination palpation of the right lower quadrant was painful but no mass was identified. She underwent a colonoscopy that was unremarkable. Pelvic and transvaginal
ultrasonography (US) were requested and demonstrated a solid left ovarian ovoid mass, measuring 40x30mm (Fig.1). Previous US obtained seven months before was normal. A small volume of free fluid was
found in the pouch of Douglas. No enlarged lymph nodes were found in the pelvic cavity. An MR study was done, confirming the US findings, demonstrating a solid mass in the left ovary (40mm maximal
diameter) with heterogeneous low-signal intensity on T1 and T2-weighted images and a discrete pattern of enhancement (less than myometrium), slightly heterogeneous (purposed diagnosis: ovarian
fibroma) (Figs.2-4). Hysterectomy with bilateral salpingo-oophorectomy was performed. On macroscopy, the tumor was solid, well-circumscribed, pedunculated and measured 4x3x2 cm (Fig.5). Section of
the tumor disclosed a yellow and firm mass (Fig.6). Ascitic fluid analysis was negative for neoplasic cells.
Thecoma is a stromal tumor composed of lipid-containing cells that resemble theca internal cells, with less than 10 percent granulosa cells. There are two types: typical thecoma and luteinized
thecoma. The later has the basic appearance of a fibroma or a typical thecoma but also contains lutein cells1. Fibromas, thecomas, and fibrothecomas are ovarian tumors of gonadal stromal
origin and may be variants of a single entity2. Typical thecomas are usually estrogenic (presenting with metromenorrhagia and abnormal vaginal bleeding), occur in postmenopausal patients
(mean age of 60 years), are rare prior puberty and uncommon before the age of 30 years. Thecomas are unilateral in 97% of the cases. They range in size from small, impalpable tumors to large solid
masses; most are 5 to 10 cm in diameter. Sectioning typically discloses a solid yellow mass; cystic change and areas of haemorrhage and necrosis occur occasionally. Calcification may be present.
Rarely, thecomas have been associated with other uterine tumors such as mullerian mixed tumors and endometrial stromal sarcomas, suggesting a possible role of estrogen production in the genesis of
those tumors1,7. Microscopically, they are composed of fibrous tissue and theca cells with abundant lipid cytoplasm. These theca cells are responsible for the estrogenic effects of these
tumors2. Generally asymptomatic, these masses are typically detected at palpation during routine gynecologic examination2. Nevertheless, in one series, 60% of the patients
presented with uterine bleeding1. In our case the patient presented with low back pain and recent constipation, which were not related to the lesion found. Ovarian thecomas are important
from an imaging standpoint because they appear as solid masses, thereby mimicking malignant neoplasms2. Occasionally they are associated with ascites and hydrothorax (Meigs’
syndrome), which is also a more common feature of malignancy3. Some cases have been described of ovary thecoma with elevated values of CA125 and CEA in association with Meigs’
syndrome or ascites which cautions us not to rely on tumor markers to differentiate benign from malignant masses4,5. At US thecomas most commonly manifest as solid, hypoechoic masses with
sound attenuation, however the US appearance is variable2. CT shows diffuse, slightly attenuating masses with poor, very slow enhancement with administration of contrast
material2. Calcified foci may be present. At MRI thecomas typically show distinct low-signal intensity on T2-weighted images, which reflects abundant collagen. Their signal intensity may
change in the presence of edema and cyst formation3. The prominent lipid component could theoretically be depicted at chemical-shift MR imaging2. Differential diagnosis has to
be made with several benign as well malignant entities such as: fibromas, solid Brenner tumor (usually made on histological examination), pedunculated uterine leiomyomas, broad ligament leiomyomas
(absence of a normal ipsilateral ovary and the presence of small follicles surrounding the mass helps identifying the ovarian origin of thecomas), ovary primary malignancy (morphologic index
score³ 5, abundant ascites, CA125 levels), Krukenberg tumors (bilaterality and prominent enhancement favor diagnosis of Krukenberg tumor) 2,3,6.
Differential Diagnosis List