Cutaneous metastasis of cholangiocellular carcinoma (CCC) is a rare occurrence and the majority of such cases develop after the placement of a percutaneous transhepatic biliary drainage (PTBD) catheter1. Most cases of PTBD catheter-related cutaneous metastatic CCC that have been reported in the literature to date have rarely included a dermatologic manifestation2. Herein, we report a case of cutaneous metastatic CCC that developed after PTBD catheter insertion. A 74-year-old male patient who had an unresectable CCC visited our dermatology clinic for evaluation of a firm, 2 cm-sized, erythematous and hyperpigmented nodule on his right abdomen. The nodule had developed on the exit site of a former indwelling PTBD catheter. The catheter had been inserted one year prior and was removed after 5 months. A percutaneous transhepatic gallbladder drainage catheter had then been inserted near the exit site of the former PTBD catheter. The nodule had appeared 6 months after the removal of the PTBD catheter and it had gradually increased in size (Fig. 1). The patient had a medical history of malignancies associated with percutaneous indwelling catheters; therefore, we performed a skin biopsy on the nodule to determine if it was a possible skin metastasis or a hypertrophic scar. The histopathology results identified well-developed glands composed of atypical tumor cells between the sclerotic scar tissues (Fig. 2). Based on the clinical and histologic findings, we made a diagnosis of metastatic CCC resulting from PTBD catheter insertion. PTBD is commonly used in the treatment of malignant biliary obstruction and catheter-related cutaneous metastasis on the PTBD exit site has been only rarely reported since the 1980s3. Catheter-related metastasis can develop at all sites along the catheter tract, from the insertion site to the exit site4. Recently, Takahashi et al.5 suggested that the incidence of cutaneous metastasis related to PTBD has been rather underestimated. They reported that catheter site metastasis may recur metachronously or synchronously, and the mean time interval between catheter insertion and the onset of recurrence was 14.4 months.

As in this case, catheter-related skin metastasis usually occurs at the catheter insertion site and evolves rapidly. It can be difficult to differentiate between this metastasis and a hypertrophic scar. Therefore, clinicians should make careful observations and meticulously evaluate, by histopathology, any suspicious skin lesion associated with a PTBD catheter.