Primary ascending colon cancer accompanying skip metastases in left shoulder skin and left neck lymph node: A case report

BACKGROUND: Lymph node skip metastases are common in lung, breast, and thyroid cancer patients, but are rare in colon cancer patients. Specifically, lymph node skip metastases occur in 1%-3% of colon cancer patients. Previous reports have demonstrated colon cancer skip metastases involving the retropancreatic and portocaval lymph nodes and Virchow's node; however, reports involving skip metastases into the left neck lymph nodes and left shoulder skin are extremely rare, as are related reports of clinical treatment and prognosis. CASE SUMMARY: A 44-year-old Chinese man was admitted to the hospital for evaluation of persistent shoulder pain for 3 d and a cutaneous mass (3.0 cm × 2.0 cm) on the left shoulder. The left shoulder cutaneous mass was excised and bisected, revealing tissues with a fish-like appearance. The pathologic diagnosis of the cutaneous mass suggested a signature [CDX-2 (++), CK20 (++), Ki-67 (+) > 50%] of infiltrating or metastatic colorectal adenocarcinoma. An enhanced computed tomography scan of the abdomen revealed chronic appendicitis with fecal stone formation, cecal edema, and a pelvic effusion. A colonoscopy revealed a cauliflower-like mass within the ascending colon area that involved the lumen. The surface of the ascending colon mass was eroded and bleeding; a biopsy was performed. The pathologic diagnosis of the colonoscopy biopsy was an ascending colon mucinous adenocarcinoma. The patient underwent a laparoscopic radical resection of the right colon based on the pathological diagnosis. The tumor was 5.0 cm × 4.5 cm × 1.8 cm in size and infiltrated the entire thickness of the intestinal wall with vascular tumor thrombi. No nerve tissue involvement was noted. The ileum and colon resection margins were negative. The postoperative pathologic analysis revealed non-metastatic involvement of ileocecal, pericolic, or peri-ileal lymph nodes. The postoperative medical examination revealed palpably enlarged lymph nodes in the left neck, and the following color Doppler ultrasound examination of the neck confirmed enlarged lymph nodes in the left neck. After surgical resection and pathologic diagnosis, a common pathologic signature consistent with resected cutaneous mass and right colon was identified, suggesting skip metastasis of left cervical lymph nodes. The patient was then treated with eight courses of chemotherapy and under follow-up evaluations for 4 years; currently, no tumor recurrences or metastases have been noted. CONCLUSION: We report an abnormal skip metastasis involving the left shoulder skin and left neck lymph node in a patient with ascending colon adenocarcinoma. Specifically, we observed non-metastatic involvement of the lymph nodes around the tumor site but with metastases to the cervical lymph nodes. The standard surgical operations were performed to resect the cutaneous mass, tumor tissue, and cervical lymph nodes, followed by chemotherapy for eight courses. The patient is healthy with no tumor recurrences or metastases for 4 years. This clinical case will contribute to future research about the abnormal skip metastasis in colon cancers and a better clinical treatment design.