Comment
Tumor metastasis to the skin accounts for approximately 2% of all skin cancers5 and typically is observed in advanced stages of cancer. In women, breast carcinoma is the most common type of cancer to exhibit this behavior.2 Invasive ductal carcinoma represents the most common histologic subtype of breast cancer overall,6,7 and breast adenocarcinomas, including lobular and ductal breast carcinomas, are the most common histologic subtypes to exhibit metastatic cutaneous lesions.8
Invasive lobular breast carcinoma represents approximately 10% of invasive breast cancer cases. Compared to invasive ductal carcinoma, there tends to be a delay in diagnosis often leading to larger tumor sizes relative to the former upon detection and with lymph node invasion. These findings may be explained by the greater difficulty of detecting invasive lobular carcinomas by mammography and clinical breast examination compared to invasive ductal carcinomas.9-11 Additionally, invasive lobular carcinomas are more likely to be positive for estrogen and progesterone receptors compared to invasive ductal carcinomas,12 which also was consistent in our case.
Cutaneous metastases of breast cancer most commonly are found on the anterior chest wall and can present as a wide spectrum of lesions, with nodules as the most common primary dermatologic manifestation.13 Cutaneous metastatic lesions commonly have been described as firm, mobile, round or oval, solitary or grouped nodules. The color of the nodules varies and may be flesh-colored, brown, blue, black, pink, and/or red-brown. The lesions often are asymptomatic but may ulcerate.2
In our case, the distribution of lesions was a unique aspect that is not typical of most cases of metastatic cutaneous breast carcinoma. The nodules appeared more scattered and involved multiple body regions, including the back, neck, and chest. Although cutaneous breast cancer metastases have been documented to extend to these body regions, a review of PubMed articles indexed for MEDLINE using the terms cutaneous metastatic lobular breast carcinoma, breast carcinoma, and metastatic breast cancer suggested that it is uncommon for these multiple areas to be simultaneously affected.4,14 Rather, the more common clinical presentation of cutaneous metastatic breast carcinoma is as a solitary nodule or group of nodules localized to a single anatomic region.14
Another notable feature of our case was the rapid development of the cutaneous lesions relative to the primary tumor. This patient developed diffuse lesions over a period of several months, and given that her mammogram performed the previous year was negative for any abnormalities, one could suggest that the metastatic lesions developed less than a year from onset of the primary tumor. A previous study involving 41 patients with a known clinical primary visceral malignancy (ie, breast, lung, colon, esophageal, gastric, pancreatic, kidney, thyroid, prostate, or ovarian origin) found that it takes approximately 3 years on average for cutaneous metastases to develop from the onset of cancer diagnosis (range, 1–177 months).14 In the aforementioned study, 94% of patients had stage III or IV disease at time of skin metastasis, with the majority of those demonstrating stage IV disease. However, it also is possible that these breast tumors evaded detection or were too small to be identified on prior imaging.14 A review of our patient’s medical records did not indicate documentation of any visual or palpable breast changes prior to the onset of the clinically detected metastatic nodules.
Conclusion
Biopsy with immunohistochemical staining ultimately yielded the diagnosis of metastatic lobular breast carcinoma in our patient. Providers should be aware of the varying clinical presentations that may arise in the setting of cutaneous metastasis. When faced with lesions suspicious for cutaneous metastasis, biopsy is warranted to determine the correct diagnosis and ensure appropriate management. Upon diagnosis of cutaneous metastasis, prompt coordination with the primary care provider and appropriate referral to multidisciplinary teams is necessary. Clinical providers also should maintain a high index of suspicion when evaluating patients with cutaneous metastasis who have a history of normal malignancy screenings.