Abdominopelvic masses in young women encompass a wide differential diagnosis, ranging from benign functional cysts to malignant ovarian neoplasms. Although most ovarian tumors in this age group are benign, the presence of endocrine manifestations such as virilization should raise suspicion for hormonally active tumors. Sertoli–Leydig cell tumors account for less than 0.5% of all ovarian neoplasms and are characterized by androgen secretion, often leading to rapid-onset hirsutism, voice deepening, and clitoromegaly [1].

A 23-year-old nulligravid woman with no relevant medical or surgical history presented to the emergency department with progressive abdominal enlargement and marked hirsutism over 12 months. Her menstrual cycles were regular, and she denied other symptoms suggestive of hyperandrogenism, including acne and alopecia.

Physical examination revealed male-pattern hirsutism, clitoral hypertrophy and a painless, mobile, predominantly solid abdominal mass extending to the umbilicus (Figure 1). Laboratory evaluation revealed markedly elevated total testosterone (517 ng/dL), free testosterone (1.94 ng/dL), and androstenedione (3.9 ng/mL), with decreased sex hormone-binding globulin (SHBG) levels (15 nmol/L). Dehydroepiandrosterone sulfate (DHEA-S), 17-hydroxyprogesterone (17-OHP), cortisol, luteinizing hormone (LH), follicle-stimulating hormone (FSH), estradiol, prolactin, and other tumor markers, including CA-125, were within normal limits. Pelvic ultrasound demonstrated a right adnexal solid lesion measuring approximately 20 × 15 × 10 cm with moderate vascularization (color score 3). Magnetic resonance imaging (MRI) confirmed a large right ovarian mass without contralateral adnexal or lymph node involvement (Figure 2). The patient underwent right adnexectomy with omentectomy and peritoneal cytological analysis via laparotomy. Macroscopically, the right adnexa weighed 2880 g and comprised a normal fallopian tube and an enlarged ovary measuring 198 × 147 × 97 mm, with a smooth external surface and mixed contents. Microscopically, the tumor showed heterogeneous architecture with variable cellularity. Sheets of polygonal cells with abundant eosinophilic cytoplasm were present, corresponding to Leydig cells. No lymphovascular invasion was identified, and peritoneal fluid cytology showed no abnormal cells. The final diagnosis was a moderately differentiated SLCT, FIGO stage IA. Genetic analysis identified two pathogenic/probably pathogenic variants in the DICER1 gene; both alterations were confirmed to be non-germline.

The tumor was staged as FIGO IA, and surveillance strategy was adopted. At the 6-month postoperative reassessment, total testosterone and the remaining hormonal parameters had returned to normal levels. The clinical manifestations of hyperandrogenism, including hirsutism and virilization, had completely resolved. The patient remained under clinical surveillance for more than three years after surgery, with no evidence of disease recurrence.

Sertoli–Leydig cell tumors are rare ovarian sex cord–stromal neoplasms that predominantly affect young women and may present with androgenic manifestations. Virilization, particularly when progressive or accompanied by markedly elevated testosterone, should prompt consideration of an androgen-secreting ovarian tumor. In the present case, the combination of rapidly progressive hirsutism, clitoromegaly, a large unilateral ovarian mass and marked testosterone elevation was highly suggestive of a hormonally active ovarian neoplasm. The normal DHEA-S, 17-hydroxyprogesterone and cortisol levels further supported an ovarian rather than adrenal source of androgen excess [2].

Imaging findings in SLCT are variable but commonly include a unilateral solid or mixed solid–cystic ovarian mass, with heterogeneous signal intensity reflecting the diverse histological components of these tumors [2],[3].

Definitive diagnosis is histopathological, with identification of the characteristic Sertoli and Leydig cell components being fundamental for tumor classification. The presence of Leydig cells provides an important morphological correlate for the androgen-secreting activity that underlies the clinical manifestations of virilization [4].

Molecular alterations involving DICER1 have emerged as an important feature of SLCT biology. Recent evidence indicates that somatic DICER1 RNase IIIb hotspot variants are particularly frequent in intermediately and poorly differentiated tumors [5],[6]. In a 2024 international registry study including 191 patients, somatic DICER1 variants were identified in 97% of intermediately and poorly differentiated tumors that underwent somatic testing [6]. The moderately differentiated morphology and somatic DICER1 alterations observed in the present case are therefore consistent with this established molecular association.

Treatment is primarily surgical, with the extent of surgery determined by disease stage, tumor differentiation, prognostic features, and the patient’s reproductive goals. Fertility-sparing surgery is an important consideration in young women with unilateral, early-stage disease when oncologically appropriate [2],[7]. In the present case, right adnexectomy with staging procedures achieved complete surgical management of FIGO stage IA disease while preserving the contralateral ovary and uterus. This approach is particularly relevant in a 23-year-old nulligravid patient.

Prognosis is generally favorable for localized SLCT, although tumor stage, degree of differentiation, and the presence of heterologous elements influence recurrence risk. In the international registry cohort, 92% of patients presented with FIGO stage I disease, and the estimated 3-year recurrence-free survival for FIGO stage IA tumors was 93.6% [6]. A national cohort similarly reported excellent cancer-related survival among patients with localized disease, with 5-year cancer-related survival of 96% for moderately differentiated tumors [8]. The absence of lymphovascular invasion, extraovarian disease and heterologous elements in the present case, together with more than three years of follow-up without documented recurrence, is consistent with the favorable outcome expected for early-stage disease.

This case highlights the importance of recognizing progressive virilization as a potential marker of an androgen-secreting ovarian neoplasm. The combination of clinical hyperandrogenism, biochemical testosterone excess, a large unilateral ovarian mass, and the subsequent identification of somatic DICER1 alterations illustrates the value of integrating clinical, radiological, pathological, and molecular findings in the diagnosis and management of SLCT.

Sertoli–Leydig cell tumors should be considered in young women presenting with progressive virilization and an ovarian mass. Early recognition of androgen excess may facilitate diagnosis and allow fertility-sparing treatment in selected patients with early-stage disease.