Most of us will never see skin metastases from carcinoma in our clinical practices as they are relatively uncommon. It is estimated that 2% to 9% of patients with internal malignancy may develop cutaneous metastasis. Often these will herald the diagnosis of the internal malignancy.
The short article in the Advances in Skin & Wound Care Journal on this topic is a review (full reference below) of the topic. It comes out of the University of Calabar Teaching Hospital, Calabar, Nigeria. The authors had six patients with histological diagnosis of cutaneous metastatic carcinoma between 2000 to 2006. These patients were part of a wider study of cutaneous malignancy. The variables analyzed were age, sex, site of cutaneous metastasis, clinical presentation, site of primary tumor, and outcome. This was compared with total cutaneous and total malignancy.
Six cutaneous metastatic carcinomas during this period of study comprised 6.5% of total cutaneous cancer and accounted for 0.6% of total malignancy. The patients included 2 men and 4 women (male-female ratio = 1:2), and their ages ranged from 37 to 55 years (mean, 45.2 years). No patients with these lesions were in the first 3 decades of life, and the 6 patients who had these lesions were between the fourth and sixth decades.
The involved anatomic areas of the skin metastasis were chest (3), neck, anterior abdominal wall, and vulva. The primary cancers were breast (ductal) in two of the chest lesions. One of the chest lesion patients was lost to follow up prior to diagnosis of the primary.
The patient with the neck skin lesion’s primary turned out to be nasopharyngeal carcinoma. The patient with the anterior abdominal skin involvement primary was suspected to be gastrointestinal but he was lost to follow up during the evaluation. The vulval skin lesion patient’s primary turned out to be choriocarcinoma of the uterus.
The second reference below gives a much fuller review of the topic and is referenced in the first article.
The breast, stomach, lung, uterus, large intestine, and kidneys are the most frequent organs to produce cutaneous metastases. Cancers that have the highest propensity to metastasize to the skin include melanoma (45% of cutaneous metastasis cases), breast (30%), nasal sinuses (20%), larynx (16%), and oral cavity (12%). Because breast cancer is so common, cutaneous metastasis of breast cancer is the most frequently encountered type of cutaneous metastasis in most clinical practices. Although some tumors are very common, they may not necessarily eventuate in metastasis in a manner that parallels their incidence in the overall population. For example, prostate cancer is very common, but cutaneous metastasis from prostate carcinoma is relatively uncommon……..
The mortality rate is high in patients with cutaneous metastases. The appearance of cutaneous metastases signals widespread metastatic disease, resulting in a poor prognosis. Patients often survive for a short period, depending on the type of carcinoma, but this is changing. Exciting advances in chemotherapy have greatly increased survival in recent years.
Cutaneous Metastatic Carcinoma: Diagnostic and Therapeutic Values; Advances in Skin & Wound Care. 23(2):77-80, February 2010; Asuquo, Maurice E.; Umoh, Mark S.; Bassey, Ekpo E.
Metastatic carcinoma of the skin; eMedicine, August 14, 2008; Helm TN, Lee TC. (last accessed Feb 17, 2010)