Variability in mitotic figures in serial sections of thin melanomas

Area of Science:

• Dermatopathology
• Oncology
• Surgical Pathology

Background:

• T1 melanoma staging accuracy is influenced by tissue sampling methods.
• Current sampling techniques for T1 melanomas lack thorough characterization.
• Mitotic figures are key indicators in melanoma staging.

Purpose of the Study:

• To characterize the presence and distribution of mitotic figures in T1 melanomas.
• To evaluate the impact of sequential tissue sectioning on mitotic figure detection.
• To inform best practices for T1 melanoma pathological assessment.

Main Methods:

• Analysis of T1 melanomas using 5 or 10 sequential tissue sections (5-μm thickness).
• Examination of sections for the presence of mitotic figures.
• Comparison of mitotic figure detection rates between different sectioning protocols.

Main Results:

• 54% (44/82) of T1 melanomas were classified as T1b.
• Mitotic figures were present in 1 to 5 of 5 examined sections in T1b cases.
• The number of sections analyzed (5 vs. 10) did not significantly alter the detection of mitotic figures.

Conclusions:

• Reviewing 3-5 sequential sections is advisable to meet American Joint Committee on Cancer staging recommendations.
• Further research is needed to determine the prognostic significance of mitotic figure distribution in T1b melanoma.
• Potential for subclassification of T1b melanoma based on mitotic figure frequency warrants investigation.