DOI  10.17613/c6gsx-72174 

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Case Reports

Endometrial Carcinosarcoma Initially Misdiagnosed as Cervical Cancer: Case Report and Literature Review

Carrera-Holguín, Alejandra*¹; Galicia-Alemán, Brenda Lizeth¹.

*Correspondence: alejandracarreraholguin@gmail.com | ORCID: 0009-0002-2536-4137

¹General Hospital of Torreón, Torreón, Coahuila, Mexico.

Keywords: Endometrial carcinosarcoma, malignant mixed Müllerian tumor, immunotherapy, neoadjuvant therapy, radical hysterectomy

Abstract: Endometrial carcinosarcoma (ECS), or malignant mixed Müllerian tumor, is a rare and aggressive uterine cancer representing <5% of corpus malignancies. It contains both carcinomatous and sarcomatous elements and may show heterologous differentiation.

We present the case of a 71-year-old postmenopausal woman with abnormal uterine bleeding, weight loss, and a pelvic mass. Initial cytology and imaging suggested advanced cervical cancer, for which she received neoadjuvant therapy with carboplatin, bevacizumab, and pembrolizumab. Subsequent imaging revealed a mass of endometrial origin. The patient underwent radical hysterectomy with bilateral salpingo-oophorectomy. Histopathology confirmed a high-grade endometrial carcinosarcoma with serous papillary carcinoma and rhabdomyosarcomatous differentiation, staged as FIGO IIIB.

This case illustrates the diagnostic challenges of ECS, particularly its ability to mimic cervical cancer. It emphasizes the importance of histological confirmation before initiating therapy. A multimodal treatment approach combining chemotherapy, surgery, and immunotherapy may benefit selected advanced cases.

INTRODUCTION

Endometrial carcinosarcoma (ECS) is a rare but aggressive uterine malignancy, representing 2–5% of corpus cancers. Histologically, it comprises a carcinomatous component—typically serous or endometrioid—and a sarcomatous element, which may be homologous or heterologous (e.g., rhabdomyosarcoma, chondrosarcoma).

Current evidence supports a monoclonal epithelial origin with subsequent sarcomatous transdifferentiation, corroborated by overlapping molecular alterations such as TP53 and PIK3CA mutations. ECS generally affects postmenopausal women, often presenting with abnormal bleeding or a pelvic mass. Delays in diagnosis are common due to non-specific symptoms and imaging that may resemble other gynecologic malignancies.

Optimal management includes cytoreductive surgery and platinum-based chemotherapy. Immunotherapy and targeted agents are emerging options in selected cases.

CASE PRESENTATION

A 71-year-old multiparous woman (G6P5A1) with untreated hypertension reported postmenopausal bleeding, abdominal distension, anorexia, and unintentional weight loss over three months. On examination, a non-tender 10 cm hypogastric mass and an exophytic cervical lesion involving the mid-vagina were noted. No lymphadenopathy was observed.

Cervical cytology indicated squamous cell carcinoma. Based on clinical and radiologic findings, she was initially diagnosed with stage IIIB cervical cancer. She received neoadjuvant therapy (carboplatin, bevacizumab, pembrolizumab) with partial response.

A follow-up CT scan revealed a heterogeneous endometrial mass. Surgical management included radical hysterectomy with bilateral salpingo-oophorectomy and pelvic cytoreduction.

Pathology identified a 6.2 cm polypoid tumor with deep myometrial invasion, cervical involvement, and lymphovascular space invasion. Histologically, it comprised serous papillary carcinoma and rhabdomyosarcomatous differentiation. Final staging: FIGO IIIB.

The patient is under multidisciplinary follow-up for evaluation of adjuvant therapy.

DISCUSSION

ECS, also known as malignant mixed Müllerian tumor, has a worse prognosis than other endometrial carcinomas. Heterologous sarcomatous elements (e.g., rhabdomyosarcoma) portend poorer outcomes. Molecular studies confirm monoclonality, with mutations shared between epithelial and mesenchymal components.

This case illustrates diagnostic pitfalls when ECS mimics cervical carcinoma. Cytology and imaging alone may mislead; histologic confirmation is essential.

Optimal cytoreduction improves survival. For unresectable cases, neoadjuvant chemotherapy may enable surgery. Combination therapies with pembrolizumab have shown efficacy in advanced endometrial cancer, including carcinosarcoma subtypes.

Population data confirm that ECS is associated with lower survival rates. A comprehensive approach combining surgery, systemic therapy, and immunotherapy offers the best outcomes in selected patients.

CONCLUSION

ECS is an aggressive malignancy with diagnostic challenges and poor prognosis. Misdiagnosis as cervical cancer can delay appropriate treatment. This case emphasizes the value of biopsy confirmation and the potential benefits of a multimodal therapeutic strategy.