Merkel cell carcinoma of skin-current controversies and recommendations

The review covers the current recommendations for Merkel cell carcinoma (MCC), with detailed discussion of many controversies. The 2010 AJCC staging system is more in-line with other skin malignancies although more complicated to use. The changes in staging system over time make comparison of studies difficult. A wide excision with margins of 2.5–3 cm is generally recommended. Even for primary </= 1 cm, there is a significant risk of nodal and distant metastases and hence sentinel node biopsy should be done if possible; otherwise adjuvant radiotherapy to the primary and nodal region should be given. Difficulties of setting up trials owing to the rarity of the disease and the mean age of the patient population result in infrequent reports of adjuvant or concurrent chemotherapy in the literature. The benefit, if any, is not great from published studies so far. However, there may be a subgroup of patients with high-risk features, e.g. node-positive and excellent performance status, for whom adjuvant or concurrent chemotherapy may be considered. Since local recurrence and metastases generally occur within 2 years of the initial diagnosis, patients should be followed more frequently in the first 2 years. However delayed recurrence can still occur in a small proportion of patients and long-term follow-up by a specialist is recommended provided that the general condition of the patient allows it. In summary, physician judgment in individual cases of MCC is advisable, to balance the risk of recurrence versus the complications of treatment

Expression of developmentally regulated transcription factors in Merkel cell carcinoma

We have examined a number of developmentally regulated transcription factors for expression in Merkel cells and MCC cell lines and demonstrated that their expression patterns may be prognostic in MCC. We have shown that human Merkel cells from adult scalp hair follicle and from neonatal foreskin epidermal sheets express Brn-3c and HATH1. In addition, results demonstrate that the novel Merkel binding activity complex MNF contains Brn-3c. Moreover, Classic lines which retain neuroendocrine phenotype, are slow growing in culture, grow in suspension and are thought to be less aggressive, retain Brn-2, Brn-3c and HATH1 expression, whereas Variant suspension lines which no longer express NE markers retain Brn-2 and Brn-3c expression, but lack HATH1. Further, Type IV Variant lines which grow as adherent monolayers have shorter doubling times, are more radiation- resistant and have higher cloning efficiencies in soft agar, all thought to be indicative of aggressive tumours, have reduced or no Brn-2 proteins and lack expression of Brn-3c and HATH1 transcription factors.No Full Tex