What are the dermatoscopic features of possible melanoma, presenting with fissures, ridges, and comedo-like openings?

From the Guidelines

No, these dermatoscopic features (fissures, ridges, and comedo-like openings) are not typical of melanoma but are characteristic of seborrheic keratosis. The diagnosis of melanoma is typically based on the 'ABCD rule' which includes Asymmetry, Border irregularities, Colour heterogeneity, and Dynamics 4, as outlined in the ESMO clinical practice guidelines for diagnosis, treatment, and follow-up of cutaneous melanoma 1. Dermoscopy by an experienced physician enhances the diagnostic accuracy [II, B] 1, and melanomas often present with distinct features such as asymmetry, atypical network, blue-white veil, irregular dots/globules, irregular streaks, and irregular vessels. Key characteristics of melanoma include:

• Asymmetry
• Border irregularities
• Colour heterogeneity
• Dynamics In contrast, seborrheic keratoses are benign epidermal tumors that commonly appear as stuck-on, waxy lesions, and on dermoscopy, they typically show:
• Fissures (brain-like appearance)
• Ridges (fingerprint-like structures)
• Comedo-like openings (keratin-filled invaginations that appear as dark dots) However, if a lesion shows mixed features or if there is clinical suspicion despite these findings, a biopsy should be performed to rule out melanoma definitively, as diagnosis should be based on a full-thickness excisional biopsy with a minimal side margin, and processing by an experienced pathology institute is mandatory 1.

From the Research

Dermoscopic Features of Melanoma

• Fissures, ridges, and comedo-like openings can be present in seborrheic keratosis (SK), but may also be seen in melanoma 2, 3
• Melanoma can display a variety of dermoscopic patterns, including atypical pigment networks, blue-white veils, pseudopods, and streaks 3
• Benign patterns such as fissures, globular pattern, crypts, comedo-like openings, and milia-like cysts can be observed in melanoma, making diagnosis challenging 3

Differential Diagnosis

• Seborrheic keratosis (SK) can mimic melanoma clinically and dermoscopically, but typically exhibits characteristic features such as milia-like cysts and comedo-like openings 4, 2
• Melanoacanthoma (MA), a pigmented variant of SK, can also mimic melanoma, but often displays crypts and comedo-like openings on dermoscopy 3
• The presence of atypical vessels, blue-white veils, or pseudopods can increase the suspicion of melanoma, even if benign patterns are present 3

Diagnostic Approach

• Dermoscopy can be a useful tool in the diagnosis of melanoma, but should be used in conjunction with clinical examination and histopathological evaluation 2, 3
• The presence of melanoma-associated features or atypical vessels on dermoscopy should prompt a biopsy to establish a diagnosis 3