Invasive lobular breast cancer with isolated scalp metastasis: excision and endocrine therapy

What happened, in summary

This 54-year-old woman visited dermatology because a pink, hairless nodule on the left side of her scalp had enlarged. She had first noticed it 5 years earlier during chemotherapy for breast cancer, when she was losing hair, but it had stayed small for years. Six years earlier, she had been treated for invasive lobular carcinoma in the upper outer quadrant of the left breast. At that diagnosis, PET/CT showed no distant metastasis. She underwent left breast-conserving surgery, and pathology showed pT3N1c disease with cancer in left axillary lymph nodes, estrogen receptor positivity, progesterone receptor positivity, and lymphovascular invasion. Adjuvant therapy included 6 cycles of doxorubicin, cyclophosphamide, and docetaxel, followed by tamoxifen and radiation to the left breast and axilla. For 6 years, regular follow-up showed no recurrence or distant metastasis. When the scalp lesion enlarged, punch biopsy showed tissue resembling her prior breast cancer, with CK7 positivity, ER positivity, and partial GCDFP-15 positivity. PET/CT showed only slight uptake in the scalp lesion and no other metastatic sites. She underwent excision of the scalp lesion, and final pathology confirmed metastatic breast cancer. Her doctors recommended scalp radiation and gonadotropin-releasing hormone agonist therapy, but she declined and chose to continue oral anastrozole. As of April 2024, follow-up showed no recurrence in the breast or scalp and no distant metastasis. The treatment approach therefore combined local removal of the metastasis with ongoing endocrine suppression. The case highlights that even a slow-growing scalp nodule can represent isolated cutaneous metastasis years after breast cancer treatment.