What happened, in summary

A 30-year-old woman with Bloom syndrome presented in April 2020 with a mass in the left axillary tail that had been present for about 5 months. The mass was excised, and pathology showed invasive ductal breast carcinoma that was hormone-receptor negative and HER2-negative, consistent with triple-negative breast cancer. A sampled lymph node was reactive rather than cancerous, and imaging did not identify another breast primary or distant malignancy.

Because of the aggressive tumor type, she received adjuvant chemotherapy and then radiotherapy to the left chest wall and axilla. Follow-up PET imaging and breast ultrasound showed no malignant lesions after breast-cancer treatment.

Eight months after completing therapy, she developed pancytopenia. Bone marrow testing diagnosed myelodysplastic syndrome with excess blasts, a separate hematologic malignancy. She received azacitidine for the myelodysplastic syndrome, but later developed febrile neutropenia and sepsis. She died at age 33. Her breast cancer had shown no malignant lesions on follow-up imaging, while the later myelodysplastic syndrome became the major subsequent illness.