Our patient is a 62-year-old post-menopausal female with past medical history of psoriatic arthritis and left breast DCIS. She is status post left lumpectomy followed by left skin-sparing mastectomy with sentinel node biopsy and reconstruction for positive margins due to multifocal low-grade DCIS, ER/PR+, HER2-. Post mastectomy margins and lymph nodes were negative for disease, however of note, the patient never started adjuvant anti-endocrine therapy.
Two years later, she presented to clinic with a chief complaint of several small nodular masses along the left mastectomy scar extending from the reconstructed nipple to the lateral axillary chest wall. Ultrasound of the palpable masses showed diffuse thickening with skin edema. Over a week-long period, the nodules progressed in number and size (20-25 in total - Figure 2) prompting histologic evaluation. A core-needle biopsy was performed but was read as fibroadipose tissue and discordant to our findings on physical exam. We then proceeded with an excisional biopsy, which showed benign fatty tissue; again, discordant with our physical exam.
MRI with and without contrast was performed (Figure 3) showing multiple areas of nodular enhancement with skin thickening and no evidence of lymphadenopathy. A second excisional biopsy was performed, removing more tissue from the lateral chest wall. Immunohistochemical stains of this sample showed: nodules with proliferation of solid and papillary plasmacytoid cells with amphophilic cytoplasm and focal pink cytoplasmic granules. The lesional cells were CK-5 - and diffusely ER/PR+, HER 2- (Ki67 18%) with absence of myoepithelial cells by p63 and smooth muscle myosin. Findings were most compatible with invasive solid-papillary carcinoma, grade 1. The case was submitted for expert consultation to Johns Hopkins Laboratories. In their test center, the lesional cells were found to be diffusely GATA-3 + with absence of myoepithelial cells by p63/SMMHC (multiplex stain). No lymphovascular invasion was identified via D2-40 and ERG immunostains.
After presentation at multidisciplinary tumor board (MTB), she was determined to have unresectable disease due to the extent of axillary and chest wall skin involved. PET/CT showed no evidence of distant disease. The consensus recommendation was to proceed with anti-endocrine therapy with an aromatase inhibitor (AI) plus cyclin-dependent kinase (CDK 4/6) inhibitor based off the phase three PALOMA-2 trial. PALOMA-2 has shown significant benefit in the progression free survival of hormone receptor positive, HER2 negative invasive breast cancers. She was initiated on letrozole 2.5 mg daily and palbociclib 125 mg daily.
Our patient is currently still undergoing neoadjuvant anti-endocrine and immunotherapy. Thus far, she has been tolerating treatment well without complication. After 6 months, she has experienced a complete clinical resolution of her nodules and an almost complete resolution of disease on restaging MRI. After discussions with out multi-disciplinary tumor board, we plan to continue current therapy for a total of 2 years with surveillance imaging. Pending adequate response to neoadjuvant therapy, we plan to proceed with definitive surgery and adjuvant radiation therapy. The extent of her disease was tattooed shortly after initiating neoadjuvant therapy in preparation for future radiation therapy.