Endometrial stromal sarcoma is a rare type of uterine malignancy. It is typically diagnosed in women during their fifth and sixth decade of life. Abdominal pain, vaginal bleeding, and menorrhagia are main symptoms, whereas a palpable abdominal mass may be detected in a number of patients. Clinical suspicion towards this tumor must be raised early. Magnetic resonance imaging, together with a biopsy obtained during curettage and subsequent histopathological examination, as well as immunohistochemistry, are crucial components of the workup.
Endometrial stromal sarcoma (ESS) is a malignant variant of endometrial stromal tumors (ESTs) and encompasses approximately 2-5% of all neoplasms originating in the endometrium, although it is rarely encountered clinical practice . Some authors established an incidence rate of 1-2 per 100,000 women , while others claim it to be as low as 1-2 per 1 million women in 1 year . Based on the degree of proliferation, ESSs are either low-grade or high-grade tumors, but all forms penetrate the myometrium of the uterus, which is the main distinguishing feature from benign forms of ESTs (endometrial stromal nodules) . However, some authors claim that all ESSs should be considered as low-grade sarcomas, and the term undifferentiated endometrial sarcomas (UES) should be used to describe high-grade tumors with an incompletely disclosed phenotype instead  . They are primarily diagnosed in women between 40-60 years of age, with low-grade tumors being more commonly identified in younger women, whereas postmenopausal females are the primary patient population of high-grade ESS     . The clinical presentation is comprised of nonspecific symptoms such as abdominal pain, vaginal bleeding, and progressive metrorrhagia in premenopausal women  . A palpable abdominal mass may be detected in up to a quarter of individuals .
Despite the rare appearance of endometrial stromal sarcoma, the physician must perform a comprehensive clinical assessment in women who report with undisclosed abdominal pain and vaginal bleeding. A detailed patient history should be obtained first, during which the duration of symptoms and their severity, as well as the menopausal status, need to be assessed. Because a palpable mass was observed in a small, but a significant number of cases, abdominal inspection and palpation must not be overlooked during the physical examination. Imaging studies must be employed as soon as possible. Ultrasonography, despite its benefits in terms of convenience and time consumption, is not a reliable tool for discriminating between uterine lesions, and it is not uncommon for endometrial stromal sarcomas to be misdiagnosed as leiomyomas    . For this reason, magnetic resonance imaging (MRI) is the recommended study, as it can confirm the presence of a lesion invading the myometrium and enlargement of the uterus . A definite diagnosis is made after obtaining a viable sample for a histopathological examination with immunohistochemistry and uterine curettage is the crucial procedure that allows proper sampling  . Expression of CD10 on immunohistochemistry is a highly specific sign for endometrial stromal sarcomas   .