Cutaneous metastases of internal malignancies: A clinicopathologic study

Background: Secondary tumor deposits in the skin represent advanced malignancy and are of uncommon occurrence. The clinical presentation of these lesions is variable, and the clinical impression is rarely correct, except in cases of known primary malignancies.
Aim: To summarize the clinical and histopathological findings in biopsy-proven cutaneous metastases.
Methods: The present study has analyzed 14 cases of cutaneous metastases from internal malignant neoplasms, excluding hematolymphoid neoplasms. The clinical parameters analyzed include presentation of deposits and their relation to the primary tumor. The histological features of cutaneous metastases were compared with the primary tumors and the frequency of common features in them were evaluated.
Results: Cutaneous metastases from internal organ malignancies showed a prevalence rate of approximately 2%. Eight cases (56%) presented as primary manifestations of the tumor; biopsy evaluation in these cases suggested the possible primary tumor site and triggered further evaluation and imaging studies. Four patients, undergoing treatment for a known malignant tumor, had recurrence of the tumor in the form of cutaneous metastatic deposits. In the remaining two patients, cutaneous metastases of the tumor appeared simultaneously with the primary neoplasm and represented a higher stage of malignancy.
Conclusions: Skin biopsy findings were significant in all cases. The morphological patterns of cutaneous metastases corresponded with the primary tumors and their evaluation helped localize unknown primary malignancies. In cases with known primaries, cutaneous metastases upstaged the malignancy and affected the prognosis.