Collision lesions
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)[1].
- They are associated with advancing age and cumulative UV-exposure[2].
- 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[2].
- 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[3].
- Using both polarized and non-polarized dermoscopy may be helpful in the diagnosis of these lesions[4][5].
Table 1 - Skin lesions or tumors with their original cell types of the different skin layers (focused only on skin lesions detectable by dermoscopy).[2]
| Layer of the Skin | Cell Type or Functional Structure | Associated Proliferations / Neoplasms |
|---|---|---|
| Epidermis | Keratinocytes | Solar lentigo Seborrheic keratosis |
| Basal cell layer (non-differentiated folliculo-sebaceous-apocrine germ) | Trichoblastoma Basal cell carcinoma | |
| Melanocytes | Melanocytic nevus Melanoma | |
| Merkel cells | Merkel cell carcinoma | |
| Dermis | Blood capillaries | Angioma |
| Melanocytes | Melanocytic (dermal or blue) nevus Melanoma | |
| Fibroblasts | Dermatofibroma Dermatofibrosarcoma protuberans | |
| Non-Langerhans cells/histiocystes | Xanthogranuloma | |
| Infundibulo-follicular-sebaceous unit | Sebaceous hyperplasia Milia cyst | |
| Myocytes | Kaposi sarcoma |
Fig 1: Skin model for collision skin tumors/lesions with benign and malignant lesions from the epidermal and dermal origin (according to 1).
Fig 2a: Collision tumor with different brown colors at the back of a 78-year-old male in dermoscopy.
Fig 2b: Description of Fig 2a: Melanocytic nevus (upper part A) with a seborrheic keratosis (lower part B).
Fig. 3a: Collision tumor with light brown, red and blue colors at the back of a 79-year-old male.
Fig 3b: Description of Fig 3a: Seborrheic keratosis (upper part A) with a basal cell carcinoma (lower part B).
- ↑ An Atlas of Dermoscopy, Second Edition. Marghoob A. et al. CRC Press; 2012.
- ↑ 2.0 2.1 2.2 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.
