Case Report: Cutaneous Metastases from Colorectal Cancer: A Rare Case of Isolated Skin Recurrence

Introduction

Cutaneous metastases from colorectal cancer (CRC) are rare, with reported incidences of 0.7–4% among metastatic cases. Their presence generally reflects advanced disease and poor prognosis. Typical metastatic sites include the liver, lungs, and peritoneum; skin involvement is far less common.

We present an unusual case of isolated cutaneous recurrence revealing systemic relapse after curative treatment for a rectosigmoid junction adenocarcinoma.

Case presentation

A 42-year-old man with no prior medical history underwent surgery for a stenosing adenocarcinoma of the rectosigmoid junction.

Initial locoregional and distant staging was negative. He underwent low anterior resection with stapled colorectal anastomosis and had an uncomplicated postoperative recovery.

Histopathological examination of the resected specimen showed a moderately differentiated adenocarcinoma, staged as ypT3N1b. The patient received eight cycles of adjuvant capecitabine (Xeloda), completed 18 months after surgery.

A follow-up CT scan performed three months after completion of chemotherapy showed no abnormalities. A completion colonoscopy, performed because a full preoperative evaluation had not been possible, was also normal.

Approximately five months later, the patient presented with newly developed pruritic skin lesions. Clinical examination revealed erythematous eczematous plaques in the right inguinal fold, gluteal region, and perianal area ( Figure 1). He was otherwise in good general condition (ECOG 0). Digital rectal examination was unremarkable, and serum tumor markers (CEA, CA 19-9) were within normal limits.

Figure 1. Clinical presentation of cutaneous metastases: infiltrating nodular lesions in inguinal and peri anal regions on examination.

A punch biopsy of the skin lesion confirmed metastatic adenocarcinoma consistent with colorectal origin (CK20-positive, CK7-negative, CDX2-positive) ( Figure 2A,B).

Figure 2. Histopathological and immunohistochemical features of the cutaneous metastasis: (A) Skin biopsy showing dermal infiltration by atypical glandular structures consistent with metastatic adenocarcinoma (Hematoxylin–Eosin, ×200). The asterisk (*) marks tumoral glands invading the dermis, while the arrow indicates adjacent uninvolved dermis. (B) Immunohistochemical staining showing diffuse cytoplasmic positivity for CK20 in tumor cells, confirming colorectal origin (CK20 IHC, ×200).

A thoraco-abdomino-pelvic CT scan revealed new, non-necrotic lymphadenopathy at the aortic bifurcation (22 × 9 mm) and in both internal iliac chains ( Figure 3).

Figure 3. Contrast-enhanced CT scan shows non necrotic lymphadenopathy at the aortic bifurcation (22 × 9 mm).

The case was discussed in a multidisciplinary tumor board. The presence of cutaneous metastases and retroperitoneal lymph node involvement led to classification as unresectable stage IV disease. The patient was referred for palliative systemic chemotherapy, with RAS, BRAF, and MSI testing planned to guide targeted or immunotherapeutic options.

Discussion

Cutaneous metastases from CRC are uncommon but clinically significant indicators of systemic dissemination. The median time from initial diagnosis to skin involvement ranges from 18–30 months, and median survival after diagnosis of skin metastasis is approximately 8 months.^1–3

Conclusion

Cutaneous metastases from colorectal cancer are rare and often signal systemic relapse. Awareness of this entity is essential, as lesions may mimic benign dermatologic conditions and occur even when tumor markers and imaging appear normal. Early biopsy and multidisciplinary evaluation are critical for accurate diagnosis and management.

Systemic therapy guided by molecular profiling remains the mainstay of treatment, while novel immunotherapy–anti-angiogenic combinations show promise in refractory microsatellite-stable disease. Continued reporting of such cases will aid in refining prognostic understanding and therapeutic strategies.

Patient consent

Written informed consent was obtained from the patient for publication of this case report and any accompanying images.