# Rapid Development of Breast Mass With Recurrent Episodes of Hypoglycemia Should Raise Suspicion of Breast Cancer With Insulinoma: A Case Report

## TL;DR

A case report describes a patient with breast cancer and insulinoma, highlighting the importance of recognizing rare co-occurring conditions in cancer treatment.

## Contribution

This is the first reported case of metastatic breast cancer co-occurring with insulinoma, emphasizing the need for multidisciplinary care.

## Key findings

- The patient's hypoglycemic symptoms and rapidly growing breast mass were linked to co-occurring insulinoma and breast cancer.
- Treatment with alcohol ablation and neoadjuvant therapy effectively controlled the patient's condition.
- The case highlights the importance of considering rare tumor interactions in cancer management.

## Abstract

Breast cancer ranks first in the global incidence rate of malignant tumors in women. Despite the continuous emergence of new treatment methods, it remains a significant threat to the lives and quality of life of patients. Insulinoma, a rare pancreatic neuroendocrine tumor, causes pancreatic beta cells to over‐secrete insulin, disrupting the normal physiological feedback mechanism and leading to hyperinsulinemia. Studies have demonstrated that hyperinsulinemia can promote tumor development through various pathways, posing substantial challenges to tumor treatment. However, in previous studies, no successful treatment cases of breast cancer combined with insulinoma have been reported. Therefore, we present a case of metastatic breast cancer co‐occurring with insulinoma. The patient presented with a rapidly growing mass in the left breast accompanied by recurrent hypoglycemic symptoms. Following our treatment, the condition was significantly and effectively controlled.

A 57‐year‐old female with a rapidly enlarging mass in the left breast for over 1 year, currently measuring approximately 11 × 10 × 8 cm, with multiple enlarged and fused lymph nodes palpable in the ipsilateral axilla and bilateral neck. She had a history of recurrent hypoglycemic symptoms for 2 years, confirmed by laboratory tests, imaging examinations, fine needle aspiration biopsy (FNA), as metastatic breast cancer combined with insulinoma. On August 3, 2023, she underwent ultrasound‐guided alcohol ablation of the insulinoma and complete neoadjuvant therapy for breast cancer. The hypoglycemic symptoms disappeared and the tumor was rapidly and effectively controlled. Unfortunately, due to economic reasons, the patient refused further surgical treatment.

The unique aspect of this case lies in the rapid growth of a breast mass over a one‐year period, accompanied by recurrent episodes of hypoglycemia. Following clinical evaluation, the diagnosis was metastatic breast cancer with concomitant insulinoma. To our knowledge, reports of similar cases are scarce. This case underscores the importance for clinicians to remain vigilant when encountering rapidly progressing cancers, particularly in identifying various factors that may contribute to cancer development. When multiple diseases coexist, it is crucial to recognize the interrelationships between these conditions and to adopt a multidisciplinary approach to treatment, thereby striving to provide the best personalized care for patients.