Merkel cell carcinoma of skin-current controversies and recommendations

Abstract

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.

Merkel cell carcinoma in a 17-year-old boy, report of a highly aggressive fatal case and review of the literature

“… 17 Tumor staging has been extensively introduced in previous reports. 18 Stage of the tumor has been reported to correlate with 10-year survival. 18 MCC has a propensity to metastasize to many sites, particularly lymphnodes, lung, liver, brain and bone.…”

Merkel cell carcinoma of the abdominal wall

“…In 2010, American Joint Committee on Cancer released its first consensus staging system for MCC and is reported in the literature. [ 31 ] The present case was pT3N1bMx (over 5 cm maximum tumor dimension with macrometastasis in regional lymph nodes), stage IIIB.…”

Brief S2k guidelines – Merkel cell carcinoma

“…For primary tumors without signs of organ metastases, complete surgical excision is considered basic therapy. Given the high rate of local recurrences, which generally are due to subclinical satellite metastases, a safety margin of 2 cm is desirable . At certain sites, where only a small safety margin is possible, complete histological inspection of the margins of the excised material (e. g., with 3D histology), including immunohistology, and if necessary radiation treatment, should be performed .…”

“…Whether the need for a sentinel node biopsy should be based on tumor size or on other characteristics is still under discussion. The majority of publications report lymph node involvement even with small tumors, so that a sentinel node biopsy is generally recommended for all patients . Given the very high rate of lymphogenous metastasis of MCC in the head/neck region, should a sentinel node biopsy not be performed, a functional neck dissection should be considered.…”

“…The usefulness of FDG or DOTATOC‐PET studies as a part of follow‐up has not yet been established. The follow‐up period is generally 5 years given that the majority of recurrences occur during this time .…”