In women, breast cancer is the leading cancer diagnosis and the second leading cause of cancer-related death,1 as well as the most common malignancy to metastasize to the skin.2 Cutaneous breast carcinoma may present as cutaneous metastasis or can occur secondary to direct tumor extension. Five percent to 10% of women with breast cancer will present clinically with metastatic cutaneous disease, most commonly as a recurrence of early-stage breast carcinoma.2
In a published meta-analysis that investigated the incidence of tumors most commonly found to metastasize to the skin, Krathen et al3 found that cutaneous metastases occurred in 24% of patients with breast cancer (N=1903). In 2 large retrospective studies from tumor registry data, breast cancer was found to be the most common tumor involving metastasis to the skin, and 3.5% of the breast cancer cases identified in the registry had cutaneous metastasis as the presenting sign (n=35) at time of diagnosis.4
We report an unusual presentation of cutaneous metastatic lobular breast carcinoma that involved diffuse cutaneous lesions and rapid progression from onset of the breast mass to development of clinically apparent metastatic skin lesions.
A 59-year-old woman with an unremarkable medical history presented to our dermatology clinic for evaluation of new widespread lesions that developed over a period of months. The eruption was asymptomatic and consisted of numerous bumpy lesions that reportedly started on the patient’s neck and progressively spread to involve the trunk. Physical examination revealed multiple flesh-colored, firm nodules scattered across the upper back, neck, and chest (Figure 1). Bilateral cervical and axillary lymphadenopathy also was noted. Upon questioning regarding family history of malignancy, the patient reported that her brother had been diagnosed with colon cancer. Although she was not up to date on age-appropriate malignancy screenings, she did report having a diagnostic mammogram 1 year prior that revealed a suspicious lesion on the left breast. A repeat mammogram of the left breast 6 months later was read as unremarkable.
Two 3-mm representative punch biopsies were performed. Hematoxylin and eosin staining revealed a basket-weave stratum corneum with underlying epidermal atrophy. A relatively monomorphic epithelioid cell infiltrate extending from the superficial reticular dermis into the deep dermis and displaying an open chromatin pattern and pink cytoplasm was observed, as well as dermal collagen thickening. Linear, single-filing cells along with focal irregular nests and scattered cells were observed (Figure 2). Immunohistochemical staining was positive for cytokeratin 7 (Figure 3A), epithelial membrane antigen, and estrogen receptor (Figure 3B) along with gross cystic disease fluid protein 15; focal progesterone receptor positivity also was present. Cytokeratin 20, cytokeratin 5/6, carcinoembryonic antigen, p63, CDX2, paired box gene 8, thyroid transcription factor 1, and human epidermal growth factor receptor 2/neu stains were negative. Findings identified in both biopsies were consistent with metastatic cutaneous lobular breast carcinoma.
A complete blood cell count and complete metabolic panels were within normal limits, aside from a mildly elevated alkaline phosphatase level. Breast ultrasonography was unremarkable. Stereotactic breast magnetic resonance imaging (MRI) revealed a 9.4-cm mass in the upper outer quadrant of the right breast as well as enlarged lymph nodes 2.2 cm from the left axilla. A subsequent bone scan demonstrated focal activity in the left lateral fourth rib, left costochondral junction, and right anterolateral fifth rib—it was unclear whether these lesions were metastatic or secondary to trauma from a fall the patient reportedly had sustained 2 weeks prior. Lumbar MRI without gadolinium contrast revealed extensive abnormal heterogeneous signal intensity of osseous structures consistent with osseous metastasis.
Subsequent diagnostic bilateral breast ultrasonography and percutaneous left lymph node biopsy revealed pathology consistent with metastatic lobular breast carcinoma with near total effacement of the lymph node and extracapsular extension concordant with previous MRI findings. The mass in the upper outer quadrant of the right breast that previously was observed on MRI was not identifiable on this ultrasound. It was recommended that the patient pursue MRI-guided breast biopsy to have the breast lesion further characterized. She was referred to surgical oncology at a tertiary center for management; however, the patient was lost to follow-up, and there are no records available indicating the patient pursued any treatment. Although we were unable to confirm the patient’s breast lesion that previously was seen on MRI was the cause of the metastatic disease, the overall clinical picture supported metastatic lobular breast carcinoma.