From dermoscopedia

This is the page on the glossary term Collsion which is relevant on dermoscopedia. See also the list of terms.


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Collision tumors/lesions of the skin, detectable with dermoscopy, can occur in all possible combinations of the different cells of the epidermal and/or dermal cell layers (Table 1, Figure 1) (1).

  • Combinations of epidermal-epidermal collision tumors are more often found in UV-exposed skin areas in older patients than epidermal-dermal combinations.
  • To diagnose correctly any possible collision tumor/lesion, the dermoscopic analysis of colors and differential structures must be perfomed in all four "quadrants" (2,3).
  • The switch between polarized and non-polarized light might also be helpful (4,5).

Skin lesions or tumors with their original cell types of the different skin layers (focused only on skin lesions detectable by dermoscopy) (1).

Layer of the Skin Cell Type or Functional Structure Associated Proliferations / Neoplasms
Epidermis Keratinocytes Solar lentigo

Seborrheic keratosis
Actinic keratosis
Bowen's disease
Squamous cell carcinoma

Basal cell layer (non-differentiated folliculo-sebaceous-apocrine germ) Trichoblastoma

Basal cell carcinoma

Melanocytes Melanocytic nevus


Merkel cells Merkel cell carcinoma
Dermis Blood capillaries Angioma
Melanocytes Melanocytic (dermal or blue) nevus


Fibroblasts Dermatofibroma

Dermatofibrosarcoma protuberans

Non-Langerhans cells/histiocystes Xanthogranuloma
Infundibulo-follicular-sebaceous unit Sebaceous hyperplasia

Milia cyst
Adnexal (benign or malignant) tumor

Myocytes Kaposi sarcoma

References: [1][2][3][4][5][6][7]

  1. An Atlas of Dermoscopy, Second Edition. Marghoob A. et al. CRC Press; 2012.
  2. Blum A, Siggs G, Marghoob AA, et al. (2017) Collision skin lesions-results of a multicenter study of the International Dermoscopy Society (IDS). Dermatol Pract Concept 2017;7(4):12;51-62
  3. Braga JC, Scope A, Klaz I, Mecca P, Spencer P, Marghoob AA. Melanoma mimicking seborrheic keratosis: an error of perception precluding correct dermoscopic diagnosis. J Am Acad Dermatol 2008:58:875-880
  4. Kittler H, Marghoob AA, Argenziano G, 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;74:1093-1106
  5. Wang SQ, Dusza SW, Scope A, Braun RP, Kopf AW, Marghoob AA. Differences in dermoscopic images from nonpolarized dermo¬scope and polarized dermoscope influence the diagnostic accuracy and confidence level: a pilot study. Dermatol Surg 2008;34:1389-1395
  6. Pan Y, Gareau DS, Scope A, Rajadhyaksha M, Mullani NA, Mar¬ghoob AA. Polarized and nonpolarized dermoscopy: the explana¬tion for the observed differences. Arch Dermatol 2008;144:828-829.
  7. Blum A, Maltagliati-Holzner P, Deinlein T, Hofmann-Wellenhof R. Collision tumors in dermoscopy : A new challenge. Hautarzt 2018 May 4. doi: 10.1007/s00105-018-4172-z.