biostudies-literatureUnknown81(3)Vernemmen AIPMaastricht UniversityUniversiteit Maastricht<h4>Aims</h4>Cutaneous metastases of internal malignancies occur in 1-10% of cancer patients. The diagnosis can sometimes be challenging, especially in cases with an unknown primary cancer.<h4>Materials and methods</h4>A retrospective case review was performed including all cases of skin metastases from primary internal malignancies diagnosed at the Department of Pathology at the Maastricht University Medical Centre+ from 2007 to 2021. The clinicopathological data were collected and immunohistochemical and molecular diagnostic tests were performed to confirm the primary origin of the metastases.<h4>Results</h4>We identified 152 cases (71 female; 31 male patients) of cutaneous metastases of internal malignancies. 28 patients (20 women and 8 men) were diagnosed with multiple cutaneous metastases. Among the female patients, the most common primary tumour was breast cancer (50% of the cases), followed by lung (13.6%), gynaecological (7.3%), and gastrointestinal origin (7.3%). Among the male patients, the most common primary sites were gastrointestinal and lung origin (altogether, 50% of the cases). In 19 patients, the cutaneous metastasis was the first presentation of a clinically silent internal malignancy (18.6%), of which most (78.9%) represented metastatic lung carcinomas. Finally, metastasizing patterns were different across tumour types and gender.<h4>Conclusion</h4>Breast, lung, gastrointestinal, and gynaecologic cancers are the most common primary tumours demonstrating skin metastases. Infrequently, cutaneous metastases can be the first clinically visual manifestation of an underlying not yet diagnosed internal malignancy; therefore, occasional broad immunohistochemical profiling, molecular clonal analysis, and a continuous high level of awareness are necessary for a precise diagnosis of cutaneous metastases of internal malignancies.Histopathology329-341https://www.ebi.ac.uk/biostudies/studies/S-EPMC9544513biostudies-literatureCutaneous metastases of internal malignancies: a single-institution experience.PMC9544513Kubat BHausen AZLi XRoemen GMJMWinnepenninckx VJLVernemmen AIPSamarska IVSpeel EMfalseCutaneous metastases of internal malignancies: a single-institution experience.<h4>Aims</h4>Cutaneous metastases of internal malignancies occur in 1-10% of cancer patients. The diagnosis can sometimes be challenging, especially in cases with an unknown primary cancer.<h4>Materials and methods</h4>A retrospective case review was performed including all cases of skin metastases from primary internal malignancies diagnosed at the Department of Pathology at the Maastricht University Medical Centre+ from 2007 to 2021. The clinicopathological data were collected and immunohistochemical and molecular diagnostic tests were performed to confirm the primary origin of the metastases.<h4>Results</h4>We identified 152 cases (71 female; 31 male patients) of cutaneous metastases of internal malignancies. 28 patients (20 women and 8 men) were diagnosed with multiple cutaneous metastases. Among the female patients, the most common primary tumour was breast cancer (50% of the cases), followed by lung (13.6%), gynaecological (7.3%), and gastrointestinal origin (7.3%). Among the male patients, the most common primary sites were gastrointestinal and lung origin (altogether, 50% of the cases). In 19 patients, the cutaneous metastasis was the first presentation of a clinically silent internal malignancy (18.6%), of which most (78.9%) represented metastatic lung carcinomas. Finally, metastasizing patterns were different across tumour types and gender.<h4>Conclusion</h4>Breast, lung, gastrointestinal, and gynaecologic cancers are the most common primary tumours demonstrating skin metastases. Infrequently, cutaneous metastases can be the first clinically visual manifestation of an underlying not yet diagnosed internal malignancy; therefore, occasional broad immunohistochemical profiling, molecular clonal analysis, and a continuous high level of awareness are necessary for a precise diagnosis of cutaneous metastases of internal malignancies.2022-01-01T00:00:00Z2022 Sep2025-04-04T20:03:58.196Z2025-04-04T20:03:58.196ZS-EPMC95445133575818610.1111/his.14705