Colonic adenocarcinoma presenting as a cutaneous metastasis in an old operative scar.

PK Wright, MK Jha, PD Barrett, IM Bain 
 Departments of General Surgery and Pathology, University Hospital of North Durham, North Road, Durham, DH1 5TW, UK.

Correspondence Address:
P K Wright
Departments of General Surgery and Pathology, University Hospital of North Durham, North Road, Durham, DH1 5TW, UK.

Full Text

Cutaneous metastasis from colon cancer is uncommon and typically signifies widespread disease and poor prognosis. In colon cancers, cutaneous metastases usually occur after identification of the primary tumour, although several cases have been described with this as the mode of presentation.[1],[2] Although numerous cases of metastatic colon cancer in operative scars following tumour resection by open and laparoscopic colectomy have been reported, to our knowledge there is only one reported case of colon cancer presenting with cutaneous metastasis in a pre-existing operative scar.[6],[7] We describe one further case.

::   Case history

An 81-year-old woman was referred to University Hospital of North Durham with a one month history of noticing a lump in the skin of her anterior abdominal wall in the region of previous cholecystectomy scar. On questioning she also described vague right-sided abdominal pain over the same time period. She had no other symptoms including altered bowel habit or bleeding per rectum. Her past medical history included an open cholecystectomy through a subcostal incision eighteen years ago. Physical examination revealed mild anaemia and a firm cutaneous nodule in the middle of the cholecystectomy scar. Abdominal CT scan showed an intussuscepting caecal tumour with a solitary nodule 23mm in diameter in the subcutaneous tissue of the right upper abdomen with the appearances of a cutaneous metastasis [Figure:1]. The patient underwent laparotomy, right hemicolectomy and excision of the cutaneous nodule.

Histopathological examination of the bowel specimen showed a primary moderately differentiated colonic adenocarcinoma of mucinous type. Tumour was identified immediately beneath the serosa although the serosal surface was not breached. Three out of fourteen lymph nodes contained metastatic deposits and extramural lymphatic invasion was apparent. The cutaneous specimen contained a central nodule of adenocarcinoma with histological features identical to the primary colonic tumour.

::   Discussion

The most frequent site of cutaneous metastasis from colonic adenocarcinoma is the abdomen, although other sites have been described including extremities, penis, head and neck.[1],[2],[3],[4],[5] Cutaneous metastases in operative scars generally occur in the incisions used for tumour resection, rather than in a pre-existing scar.[6]

Several mechanisms of cutaneous metastasis have been proposed, including direct extension, haematogenous spread, lymphatic spread, spread along ligaments of embryonic origin and implantation of exfoliated tumour cells. Tumour cell implantation may be the most likely pathogenesis when there is metastasis to incisions created for tumour resection via laparoscopic or open colectomy.[6] However, in the authors’ opinion this is unlikely in our case as at the time of cholecystectomy the tumour almost certainly was either at an early stage or may not have existed, precluding the availability of tumour cells for seeding. Perhaps a more feasible mechanism would be that of spread along the ligaments of embryonic origin as the metastasis occurred at a site close to the falciform ligament. Alternatively an alteration in local lymphatic drainage in the region of the scar may be the mechanism responsible for encouraging tumour cell implantation. Although haematogenous metastasis is possible, the question that has to be asked is why should metastasis occur in the scar as opposed to elsewhere? There is little to suggest direct spread as the pathogenic process involved in this case as there was no contiguous tumour.

Assuming that it was not a random phenomenon, we suggest that there was a predilection to incisional metastasis, either as a result of an alteration in the microscopic anatomy around the scar, perhaps in the lymphatic channels, or that the local environs of the scar were more receptive to metastatic tumour cells, possibly due to altered adhesion molecule profile or altered local immunosurvei-llance mechanisms. The exact pathogenesis of incisional metastasis remains a matter of speculation awaiting further recognition and investigation.

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