Random MCQ Dermatology - Melanoma staging

A 45-year-old woman presents with a changing mole on her mid-back. Dermoscopic examination reveals an asymmetric lesion with a multicomponent pattern, including an atypical pigment network, irregular streaks, and blue-white structures. A broad shave biopsy is performed. The pathology report describes a malignant melanocytic proliferation with tumor cells invading to a depth of 1.2 mm into the dermis. There is no evidence of ulceration or mitotic activity. According to the AJCC 8th edition staging system, which of the following is the most important additional histologic feature required to assign the final T-stage for this melanoma?

A) The presence of satellite metastases
B) The Breslow thickness measured in millimeters
C) The presence or absence of tumor-infiltrating lymphocytes (TILs)
D) The presence or absence of ulceration
E) The Clark level of invasion

Correct Answer: D) The presence or absence of ulceration

Explanation
(Per AJCC 8th Edition Staging Guidelines)

This question tests the critical knowledge of the T-stage criteria for cutaneous melanoma according to the most current (AJCC 8th edition) staging system.

• Breslow Thickness: The biopsy report provides the most important factor: Breslow thickness of 1.2 mm. This immediately places the tumor in the T2 category (T1: ≤1.0 mm, T2: 1.01–2.0 mm, T3: 2.01–4.0 mm, T4: >4.0 mm).

• The Key Determinant: Ulceration: However, within each T-category (T2, T3, etc.), the presence or absence of ulceration is the feature that upstages the prognosis. Therefore, the final T-stage for this 1.2 mm melanoma would be:

  • T2a if non-ulcerated.

  • T2b if ulcerated.

The absence of ulceration and mitotic activity in the report are favorable findings, but the definitive assessment of ulceration is required for precise staging.

Why Not the Other Options?

• (A) Satellite metastases: The presence of satellite or in-transit metastases is not a T-stage feature. It defines Stage IIIB/C disease (N2c or N3 category), regardless of T-stage.

• (B) The Breslow thickness: This is provided in the question (1.2 mm) and is the primary factor for determining the T-category (e.g., T1, T2, T3, T4). However, the final T-stage designation (a vs. b) requires the ulceration status.

• (C) Tumor-infiltrating lymphocytes (TILs): While the presence of a "brisk" TIL host response is a favorable prognostic factor, it is not used in the formal AJCC staging system.

• (E) The Clark level of invasion: The Clark level was removed from the AJCC 8th edition staging system due to poor reproducibility and because it was superseded in prognostic importance by Breslow thickness and ulceration. It is no longer used to assign T-stage.

Final Staging for this Patient:
With a thickness of 1.2 mm and no ulceration (T2a), and no evidence of nodal or distant spread (clinically Stage I or II), this patient would have Stage IB melanoma. If ulceration were present, it would be upstaged to Stage IIA.