Malignant phyllodes tumor in Lynch syndrome: a case report

Area of Science:

• Oncology
• Genetics
• Hereditary Cancer Syndromes

Background:

• Lynch syndrome (hereditary nonpolyposis colorectal cancer) is an autosomal dominant disorder predisposing to various cancers.
• Known Lynch syndrome-associated cancers include colorectal, endometrial, stomach, ovarian, and others.
• Malignant phyllodes of the breast is not a commonly recognized cancer associated with Lynch syndrome.

Purpose of the Study:

• To report a rare case of malignant phyllodes breast tumor in a patient diagnosed with Lynch syndrome.
• To emphasize the importance of genetic testing in identifying hereditary cancer syndromes, even with rare malignancies.
• To contribute to the understanding of the phenotypic spectrum of Lynch syndrome.

Main Methods:

• A 43-year-old woman presented with a breast lump diagnosed as a malignant phyllodes tumor.
• Genetic testing using a 25-gene panel revealed a heterozygous MSH6 mutation, indicating Lynch syndrome.
• The patient received adjuvant chemotherapy and risk-reducing surgery; family members were also tested.

Main Results:

• A rare association between malignant phyllodes breast tumor and Lynch syndrome was identified.
• The patient's MSH6 mutation confirmed Lynch syndrome, prompting further clinical management and family screening.
• Genetic testing identified the same mutation in two brothers and the patient's daughter.

Conclusions:

• This case underscores the critical role of genetic testing in diagnosing rare malignancies.
• It highlights that the full spectrum of cancers associated with known hereditary syndromes is still being defined.
• Comprehensive genetic evaluation is essential for accurate diagnosis and management of hereditary cancer predispositions.