Detectable by dermoscopy, Collision tumors/lesions of the skin can occur in all possible combinations of the different growths of the epidermal and/or dermal cell layers (Table 1 & Figure 1).
- They are associated with advancing age and cumulative UV-exposure.
- Compared with combinations of epidermal-dermal collision tumors, epidermal-epidermal collision tumors are more likely to be found in older patients and on the head and neck areas. In addtion, Collision tumors with a basal cell carcinoma component are more common on the head and neck compared to collision tumors with a melanocytic component that are more common on the trunk.
- Collision tumors pose a diagnostic challenge. To correctly diagnose any possible collision tumor/lesion, the dermoscopic analysis of colors and structures must be performed in all four "quadrants" of the inspected lesion.
- Using both polarized and non-polarized dermoscopy may be helpful in the diagnosis of these lesions.
Table 1 - Skin lesions or tumors with their original cell types of the different skin layers (focused only on skin lesions detectable by dermoscopy).
|Layer of the Skin||Cell Type or Functional Structure||Associated Proliferations / Neoplasms|
|Basal cell layer (non-differentiated folliculo-sebaceous-apocrine germ)||Trichoblastoma|
Basal cell carcinoma
|Merkel cells||Merkel cell carcinoma|
|Melanocytes||Melanocytic (dermal or blue) nevus|
|Infundibulo-follicular-sebaceous unit||Sebaceous hyperplasia|
- An Atlas of Dermoscopy, Second Edition. Marghoob A. et al. CRC Press; 2012.
- Blum et al.: Collision skin lesions-results of a multicenter study of the International Dermoscopy Society (IDS). Dermatol Pract Concept 2017;7:51-62. PMID: 29230351. DOI.
- Braga et al.: Melanoma mimicking seborrheic keratosis: an error of perception precluding correct dermoscopic diagnosis. J. Am. Acad. Dermatol. 2008;58:875-80. PMID: 18328596. DOI.
- Kittler et al.: Standardization of terminology in dermoscopy/dermatoscopy: Results of the third consensus conference of the International Society of Dermoscopy. J. Am. Acad. Dermatol. 2016;74:1093-106. PMID: 26896294. DOI.
- Wang et al.: Differences in dermoscopic images from nonpolarized dermoscope and polarized dermoscope influence the diagnostic accuracy and confidence level: a pilot study. Dermatol Surg 2008;34:1389-95. PMID: 18637816. DOI.