Collision Lesions: Genuine Collision (Conflict) or not?

Area of Science:

• Dermatology
• Oncology
• Pathology

Background:

• Collision lesions are defined as two or more tumors in the same anatomic site.
• Collision skin lesions (CSLs) specifically occur when multiple tumors coincide at the same skin location.
• CSLs present a significant diagnostic challenge in clinical practice due to their rarity and complex presentation.

Purpose of the Study:

• To elucidate the clinical problem of collision skin lesions (CSLs).
• To classify CSLs based on positional dependence, tumor histogenesis, etiology, and lesion combinations.
• To evaluate diagnostic possibilities and challenges associated with CSLs.

Main Methods:

• Review and analysis of clinical cases presenting with collision skin lesions.
• Classification of CSLs according to established dermatological and oncological parameters.
• Assessment of diagnostic accuracy based on clinical evaluation versus histopathological findings.

Main Results:

• Accurate clinical diagnosis of CSLs is rarely achieved.
• Tumors in CSLs can be partially or completely superimposed, or nested, complicating detection.
• Lesion excision followed by pathohistological confirmation is often necessary for definitive diagnosis.

Conclusions:

• Collision skin lesions are diagnostically challenging due to overlapping or nested tumor presentations.
• Clinicians must be aware of CSLs to consider this possibility in differential diagnoses.
• Histopathological confirmation after surgical excision remains the gold standard for diagnosing CSLs.