ER/PR-positive mucinous breast cancer treated with mastectomy and tamoxifen

What happened, in summary

This 36-year-old Hispanic woman was being evaluated primarily for a severe movement disorder when her medical history also included breast cancer. At age 35, during a routine physical examination, she was diagnosed with breast cancer. Pathology showed grade I encapsulated mucinous carcinoma, a breast cancer subtype in which tumor cells sit within mucin pools. The tumor cells expressed estrogen and progesterone receptors and did not overexpress HER2/neu. She underwent radical right mastectomy with preservation of the nipple and areola, followed by postoperative tamoxifen. The documented cancer course showed no local recurrence or metastasis after treatment. Her breast cancer occurred in the context of a broader neurologic and genetic syndrome. She had developmental delay, tall stature, facial dysmorphism, psychiatric illness in adulthood, and progressive dystonia with painful spasms, abnormal movements, difficulty walking, and major loss of independence. Brain MRI and routine metabolic testing were unrevealing, while molecular cytogenetic analysis identified a chromosome 13q34 duplication also present in her neurologically normal father. Whole-exome sequencing did not identify pathogenic mutations in BRCA1 or BRCA2; it found an SGCE variant that was considered a possible contributor to dystonia but not clearly pathogenic. Her dystonia improved after bilateral globus pallidus interna deep brain stimulation, although later hardware malfunction and dysphagia complicated her course. For the cancer record, the key breast cancer facts are localized ER/PR-positive, HER2-negative mucinous carcinoma treated with mastectomy and tamoxifen, with no evidence of breast cancer recurrence or metastasis in the documented follow-up. The neurologic condition dominated her overall disability, but the breast cancer itself remained controlled after local surgery and endocrine therapy.