The diagnosis of melanoma’s is one of the most controversial issues in dermatopathology. This paper addresses one of the very important issue of mitotic rate in melanoma’s. Existing guidelines attach a lot of importance to the presence of one mitosis in a melanoma. This study discusses the fallacy of such an approach and the fact that further studies are needed to determine whether the presence of one mitosis is really of any significance! (probably not).

American Journal of Dermatopathology:

POST AUTHOR CORRECTIONS, 8 August 2012

doi: 10.1097/DAD.0b013e3182604d96

Original Study: PDF Only

Mitotic Rate in Cutaneous Melanomas <=1 mm in Thickness: A Prospective Study

Litzner, Brandon R. MD; Etufugh, Chukwuemeka N. MD; Stepenaskie, Shelly MD; Hynan, Linda S. PhD; Cockerell, Clay J. MD

Published Ahead-of-Print

Abstract

The mitotic rate (MR) of malignant melanoma (MM) refers to the number of mitoses per square millimeter. Studies have suggested that it is an independent prognostic variable predicting survival in patients with MM, and it was recently included in the American Joint Committee on Cancer (AJCC) recommendations for diagnosis and treatment of MM. The AJCC melanoma staging committee recommends using the “hot-spot” approach to determine the MR, whereby it is reported as the maximum dermal mitotic figures identified in a 1-mm2 area of the melanoma. The AJCC has recommended that the MR be determined in all melanomas, irrespective of Breslow depth or other features. We aimed to quantify the MR in MM <=1 mm in thickness and to identify statistical associations between the MR, Breslow depth, and Clark level. In addition, we hoped to identify practical issues in determining the MR via the hot-spot technique. We conducted a prospective study to determine the MR, Breslow depth, and Clark level in MM <=1 mm in thickness. Seven melanomas were identified with epidermal mitoses only (7.4%). Sixteen melanomas had dermal mitoses (16.8%); of these, the majority (75.0%) contained only one mitotic figure. Seventy-nine melanomas had no dermal mitoses (83.2%). Seven lesions (7.4%) demonstrated multiple mitoses; 4 with >=2 dermal mitoses/mm2 and 3 with multiple epidermal mitoses. We conclude that thin MM with >1 mitosis/mm2 is rare and discuss practical and theoretical issues with determining the MR using the hot-spot approach.

(C) 2012 Lippincott Williams & Wilkins, Inc.