Cutaneous metastasis from primary bladder carcinoma is a rare event and carries a poor prognosis.1
The primary sites for metastatic bladder cancer are the liver, lung and bone. Our patient presented with haematuria and was diagnosed as having TCC of the bladder. Six weeks later, she developed a herpetiform rash on her neck and chest wall. Owing to the diagnostic dilemma and a suspicion of skin metastasis, a punch biopsy of the lesion was carried out, which showed a metastatic, poorly differentiated carcinoma in the dermis. Immunohistochemical analysis showed that the tumour cells were negative for oestrogen receptors and thyroid transcription factor 1, and positive for carcinoembryonic antigen, CK7 and CK20, which was consistent with metastasis from TCC of the bladder.
The site of origin has prognostic and therapeutic significance.2
Immunohistochemical methods to identify the site of origin have been used before. Cytokeratin staining is useful to identify metastasis from the lung, and urothelial and colorectal carcinomas, because tumours tend to maintain their tissue‐specific cytokeratin profile. A morphological overlap is seen in carcinomas that arise in different organs, making it challenging at times to differentiate the neoplasm by conventional histological methods. Determining the origin of metastatic carcinomas can be difficult, if not impossible.
Immunostaining patterns show a considerable overlap between various tumours. We present a list of immunohistochemical markers to discriminate metastasis originating from a variety of sites in females subjects.
The CK7+/CK20+/CA125− immunophenotype is highly characteristic of TCC of the urinary bladder.3,4
Colorectal tumours are CK7−/CK20+/CEA+.5,6
Thyroid tumours are CK7+/CK20−/TTF1+.7
Ovarian tumours are CK7+/CK20−/CEA−/CA125+.5,8
Lung tumours are CK7+/CK20−/TTF1+.2,4,9
- Exclude cutaneous metastases in patients presenting with herpetiform cutaneous lesions, specailly in eldelry population.
- A panel of antibodies should be used for immunohistochemistry in order to reach a proper diagnosis.
- Prognosis of patients with cutaneous metastatic disease is poor.
As the CK7+/CK20+ phenotype strongly favours transitional cells,3,10,11
we used this in conjunction with other immunohistochemical markers to diagnose the skin metastasis from TCC in the bladder of our patient.