Skin metastases C79.8

Lymphogenic or hematogenic metastases of primary skin malignancies or malignant tumors of other organs in the skin. In dermatological practice, metastases of internal malignancies are of differential diagnostic importance. They are rare, occurring in 0.6-10% of patients with metastatic tumors (Gschnell M et al.2024).

Their initial manifestation in the skin is often characterized by less spectacular, painless nodule formation. A cutaneous metastasis is regularly characterized by its surprising firmness.

The clinical picture observed in the final stage of tumor progression with diffuse carcinomatosis of the skin is referred to as lymphangiosis carcinomatosa. In the case of an accompanying inflammatory tissue reaction, a diffusely spreading lymphangiosis carcinomatosa is referred to as erysipelas carcinomatosum.

In >90% of patients, the tumor disease is already known when skin metastases occur.

Causing primary tumors by decreasing frequency, varied according to Lookingbill et al.

Frequency of cutaneous metastases in men (n=127 patients)

• Tumor type % metastasis
• Malignant melanoma 32%
• Lung 12%
• Colon/rectum 11%
• Oral cavity 8%
• Unknown primary 8%
• Larynx 5%
• Kidneys 5%
• Esophagus 2.4%
• Stomach 1%
• Prostate <1%

Frequency of cutaneous metastases in women (n=420 patients)

• Breast carcinoma 70%
• Malignant melanoma 12%
• Ovarian carcinoma 3.5%
• Unknown primary 3%
• Oral cavity 2.5%
• Lung 2.0%
• Colon/rectum 1.5%
• Endometrium 1.5%
• Urinary bladder 1.5%
• Uterus 0.7%

Causing primary tumors by decreasing frequency:

• Malignant melanoma
• Breast carcinoma
• Gastric carcinoma
• Uterine carcinoma
• Bronchial carcinoma
• Rectal carcinoma
• renal cell carcinoma.

Skin metastases frequently occur near the primarius, and metastases of breast carcinomas and lung carcinomas are found preferentially on the anterior aspect of the thorax.

Pelvic carcinomas preferentially metastasize perianally, and gastrointestinal carcinomas metastasize to the abdominal skin.

A special feature are umbilically localized skin metastases in intestinal malignancies (Sister Mary Joseph`s nodule - see below umbilical metastasis), which occurs per continuitatem or via the special vascular supply of the umbilical region.

In principle, however, distant metastasis far from the site of origin is also possible.

The scalp is a preferred site of metastasis for visceral tumors. In men, 2/3, in women 1/4 of all skin metastases occur in the head and neck region. In women, the origin is metastatic breast carcinoma in 70%; in men, bronchial carcinoma in 10%, and tumors of the gastrointestinal tract in 10%.

The most common are skin-coloured or red, fast-growing, broad-based papules or knots. Tendency to grow rapidly (a few weeks). Their consistency is predominantly "surprisingly" coarse. The surface is usually smooth, less often ulcerated.

A special clinical picture is provided by inflammatory carcinomas, which form erysipelas-like (Erysipelas carcinomatosum), highly inflammatory, bizarrely jagged (caused by lymphatic carcinoma infiltration) erythema or plaques. This type of metastasis is mainly found in breast carcinoma, more rarely also in tumours of the pancreas, stomach, lung, rectum and ovary. Analogous clinical pictures can also be obtained in loco-regional metastasis of malignant melanoma(Erysipelas melanomatosum).

Morphological and etiological special forms of skin metastases are listed under the following clinical names:

• Erysipelas carcinomatosum
• Erysipelas melanomatosum
• Cancer en cuirasse
• Umbilical metastasis
• alopecia neoplastica
• carcinoma teleangiectaticum
• CUP (cancer of unknown primary).

However, only in a few cases can the primary tumour be traced back to the metastasis. Therefore, the different names based on purely macroscopic criteria do not seem to make much sense. It is not uncommon for skin metastases to occur without the possibility of attributing them to a primary tumour ( CUP = Cancer of unknown primary).

Cell clusters of an invasively growing tumor located in the corium and subcutis. Characterization of the cells using immunohistological methods (use of mono- and polyclonal antibodies, e.g. CEA, S100, desmin, cytokeratin, vimentin, melanoma-associated antibodies).

Immunohistochemical markers of cutaneous metastases

Breast (ductal carcinoma: CK7, CEA, mammaglobulin, E-cadherin)

Breast (lobular carcinoma: CK7, CEA, EMA, Mamglobulin)

Breast (inflammatory carcinoma (erysipelas carcinomatosa: CD31, podoplanin)

Lung (squamous cell carcinoma: CK5/CK6)

Lung (adenocarcinoma: CK7, CEA, TTF-1, apoprotein A)

Lung (small cell carcinoma: TTF-1, CAM5.2, CK7,CK8/18)

Colorectal (adenocarcinoma: CK20, CEA, CDX2)

Stomach (adenocarcinoma: CK20, CEA, EMA, CDX2)

Kidney (RCC: AE1, AE3, MNF116, CD31,Vimentin, CD10, EMA, S100)

Prostate (adenocarcinoma: PSA, AMACR, ERG transcription factor)

Ovaries (ovarian carcinoma: CK7, PAX8, CA.125)

Thyroid gland (carcinomas: thyroglobulin, TTF-1, PAX8)

Thyroid gland/medullary(calcitonin)

Treatment of the primary tumor, if possible excision of the skin metastases. See below Erysipelas carcinomatosum, Erysipelas melanomatosum and diagnosis-oriented systemic therapy.

Electrochemotherapy: Combination of a cytostatic drug, which is applied intravenously or intratumorally, combined with the application of electrical impulses. The increase in efficacy is 80-fold for cisplatin and up to 8000-fold for bleomycon.

Further local immunotherapies can be carried out with: interleukin 2, imiquimod, miltefosine and DNCB/DCP.

1. Babacan NA et al. (2015) A Case of Multifocal Skin Metastases from Lung Cancer Presenting with Vasculitic-type Cutaneous Nodule. Indian J Dermatol 60:213
2. Challa VR et al (2014) Retrospective Study of Marjolin's Ulcer Over an Eleven Year Period. J Cutan Aesthet Surg 7:155-19asen.
3. Gschnell M et al. (2024) Cutaneous Metastases: From Epidemiology to Therapy. JDDG 22: 974-991

4. Lookingbill DP et al. (1993) Cutaneous metastases in patients with metastatic carcinoma: a retrospective study of 4020 patients. J Am Acad Dermatol 29:228-36

5. Siqueira VR et al. (2014) Cutaneous involvement as the initial presentation of metastatic breast adenocarcinoma - Case report. An Bras Dermatol 89:960-963
6. Zhou HY et al. (2014) Cutaneous metastasis from pancreatic cancer: A case report and systematic review of the literature. Oncol Lett 8:2654-2660