Cutaneous metastasis: a clinical, pathological, and immunohistochemical appraisal.

BACKGROUND

Cutaneous tumor metastasis may be the first manifestation of cancer, but more often is a harbinger of advanced disease that portends an ominous prognosis. All skin accessions over the past 10 years from a large Veterans Administration (VA) hospital were reviewed.

METHODS

Archived histories, glass slides, and the immunohistochemical battery (IHC), were assessed to determine diagnostic accuracy.

RESULTS

Of the 100,453 cases reviewed, there were a total of 77 cases (75 males and 2 females) of cutaneous metastasis from the lungs (28.6%), metastatic melanoma (18.2%), gastrointestinal tract (14.2%), genitourinary tract (10.4%), head and neck (9.1%), hematologic (5.2%), breast (5.2%), and miscellaneous (<2%). Metastasis represented the first indication of an internal malignancy in 7.8% of cases. The cutaneous sites of involvement included the head and neck (28%), the trunk (40%), the extremities (18%), and multiple sites (14%). The age range was 38-83 years, with a mean of 62 years. The average time interval between diagnosis of internal malignancy and cutaneous presentation was 33 months (range: <1 month-22 years), and the average survival following diagnosis was 7.5 months (range: <1 month-8 years). In a cohort of subjects, a truncated immunohistochemical battery consisting of CK-7, CK-20, and S-100 was consistent with the expected staining pattern of the primary source of cutaneous metastasis in 83.33% of the patients.

CONCLUSIONS

Excluding the potential for age and gender bias in this study conducted in a VA setting, cutaneous metastases represent an uncommon, deadly, and late-developing occurrence in many patients. Compared with previous studies, lung carcinoma remains the most common of the cutaneous metastases, with a relative rise in the incidence of metastatic melanoma. The immunohistochemical battery of CK-7, CK-20, and S-100 is a helpful adjunct in narrowing the differential diagnosis of the primary site of a large proportion of cutaneous metastases, particularly tumors with an epithelioid appearance such as carcinomas and melanomas.