Most Common Pathway of Metastasis of Rectal Signet Ring Cell Carcinoma to the Skin: Hematogenous

Liver represents the most common site of metastasis in patients with advanced colorectal cancer (CRC). Cutaneous metastasis is uncommon and has been documented only in 3% of patients. Most cutaneous metastases demonstrate typical histological features of adenocarcinoma, such as glandular formation and mucin production. We present the case of a 66-year-old male with Crohn's disease (CD) and stage IV rectal signet ring cell carcinoma arising in his rectal stump who presented with a painful papular bilateral groin rash. Biopsy revealed metastatic signet ring cell carcinoma. Since cutaneous metastasis in patients with advanced CRC can be easily confused with infection, especially fungal infection, physicians should be vigilant of the possibility of cutaneous metastasis. Our literature review suggests hematogenous spread as the dissemination pathway of this histological subtype of rectal adenocarcinoma to the skin. We present the first case of cutaneous metastatic signet ring cell carcinoma from a rectal stump of a patient with CD.