Despite their rarity, lesions in the mucosal areas got a challenging aspect.
They involve lips and oral cavity, perianal skin and the genital skin of the penis and vulva (1–3). This special pattern of localization is explained by the histology of the mucosal area, lacking normal keratin and granular layer. Parakeratin can be seen on histological samples.
Mainly in the genital areas, we recommend to follow the suggestion of Dr. Alfred Kopf (personal communication) to cover the dermoscope with polyvinyl chloride film, in order to avoid the contamination of dermoscope. If the immersion liquid (e.g. disinfection spray, oil, water) is not placed on the side between the PVC film and lens of the dermoscope, the dermoscopic image cannot allow performing an accurate diagnostic.
Dermoscopy of oral lesions
Non-pigmented oral lesions
The dermoscopy of non-pigmented oral lesions (Figure 1) are evidenced as proliferative (benign and malignant), inflammatory and autoimmune, infectious and anatomical variant of the lip.
Benign non-pigmented oral lesions
- The squamous benign papilloma represents a common intraoral benign neoplasia which displays white-pink cauliflower-like surface projections.
- Venous lakes and angioma appears as lacunas (A), purple (C) or combination between blue and red (D).
Malignant non-pigmented oral lesions
- Oral florid papillomatosis is a verrucous carcinoma which displays a whitish global aspect, sometimes network-like pattern.
- The squamous cell carcinoma of the lip shows many colors, reddish-purple, yellowish to brownish crust and white aspect.
Other non-pigmented oral lesions
- Fox-Fordyce spots are small white-yellowish dots clustered.
Inflammatory and immune lesions
- Mucosal lichen planus: the dermoscopy shows the equivalent of the Wickham streaks on the mucosal surface.
- Mucosal involvement in vulgaris pemphigus is non-specific, hard to be differentiated from squamous cell carcinoma.
Sexually transmitted diseases- Syphilis
- Primary change as a extragenital localization: homogenous purple red if Hunterian, whitish structureless if atypical.
- Secondary mucosal plaques are red-whitish and humid.
Pigmented oral lesions
Displays different aspects depending on the pigmentation: constitutive and acquired, benignant and malignant.
Benign pigmented oral lesions
Constitutive (natural) pigmentation
- Shows a homogenous (structureless) aspect, dark brown, violaceous and a combination between brown and sometimes gray.
- Shows even parallel pattern, with linear distribution of pigmentation, even structure less (light brown) or homogenous light brown color.
- It is brown-black homogenous, sometimes with a honeycomb pattern, but nor having a pigmented network pattern.
- They have to be differentiate from mucosal macule and sometimes this is difficult. Dermoscopically they display pigmented network (reticular pattern) and dotted-globular pattern. Few colors and the lack of structureless areas.
Pigmentations of the oral mucosa
- They are common in IV, V, Vi skin types (4) and rare to Caucasians. Gingivae and buccal mucosae are the most common sites for oral pigmentations. A study (4) conducted on 1,275 patients did not find mucosal melanoma and have split the pigmented pathology in oral area into: racial pigmentation, amalgam tattoo, focal melanotic macules, postinflammatory pigmentation, pigmentation due to medications, heavy metal deposits, and oral nevus.
Malignant pigmented oral lesions
Mucosal melanoma or any other malignancy
- They must be excluded when dermoscopically the combination of blue, gray, or white color with structureless zones are visible. Even blue, gray, or white color alone could be a hint for any malignancy. Often the malignant lesions are asymmetric with a disorganized pattern.
Dermoscopy of genito-anal lesions
Non-pigmented genito-anal lesions
Benign non-pigmented genito-anal lesions
- Violaceous, red or combination red-blue, red-black, homogenous pattern.
- It has the same aspect as in oral localization.
- It has the same dermoscopic pattern as in the normal skin: e.g. lichen planus, lichenus sclerosus et atrophicans, psoriasis, vitiligo.
Sexually transmitted diseases
- e.g. primary syphilis, non pigmented genital warts (HPV infection), secondary syphilis.
- In molluscum contagiosum, Seize and coworkers found (5) that at clinical examination and dermoscopy of 211 lesions, orifices were visualized in 50.2% and 96.7% of the lesions, and vessels in 6.2% and 89.1%, respectively. The vascular patterns found in the 188 lesions in which vessels were found at dermoscopy were the crown (72.3%), radial (54.3%) and dotted patterns (20.2%). Half of the 188 lesions had a combination of vascular patterns, with the flower pattern (a new vascular pattern) being found in 19.7% of cases. More orifices and vessels were identified at dermoscopy than at clinical examination, including cases with inflammation or perilesional eczema and small lesions. Dotted vessels were associated with inflammation, excoriation and perilesional eczema.
- The dermoscopy of non-pigmented warts in male population (6) shows a non-specific pattern, or a fingerlike pattern, a mosaic and oval with projections pattern. Different vessels are seen (glomerular, hairpin/dotted) in many cases, but not in all of them.
Malignant non-pigmented genito-anal lesions
- Cerebriform pattern, lack of multicomponent pattern (7) and bowenoid papulosis.
- Bowenoid papulosis (BP) corresponds to an in situ squamous cell carcinoma (SCC) located in the anogenital region. It is related to HPV and presents dermoscopically a linear arrangements of brown-grey dots or simply grey dots and dotted vessels which are widespread (8).
- The Queyrat erythroplasia, the genital verrucous carcinoma (Buschke-Lowenstein tumor) or the invasive genital squamous cell carcinoma display structureless areas, many colors and chaotic non-pigmented dermoscopic features.
- Even non-pigmented melanomas could be diagnosed dermoscopically (11): structureless and polymorphia of vessels are the hint herefor.
- They are non-specific, peculiar being shown as slate-blue if non-pigmented or reddish.
Pigmented genito-anal lesions
Benign pigmented genito-anal lesions
- The differentiation between benignant lesions (vulvar/penile melanosis, vulvar/penile nevi), and malignant pigmented ones (e.g. mucosal melanoma, pigmented Bowen`s disease) is essential.
- The benign melanosis of the mucosa presents organized pattern (parallel and also reticular or ring-like) (1,7,9).
Malignant pigmented genito-anal lesions
- Mucosal melanoma or any other malignancy must be excluded when dermoscopically the combination of blue, gray, or white color with structureless zones are visible. Even blue, gray, or white color alone could be a hint for any malignancy. Often the malignant lesions are asymmetric with a disorganized pattern.
- In the darker skin pigmentation (constitutive) homogenous brown-greyish aspect is present.
Differentiation of mucosal lesions
For non-experts in dermoscopy it is difficult to check for all these patterns in order to differentiate between benignant and malignant lesions in mucosal areas. Therefore, we propose a simplified rule on mucosal:
- The combination of blue, gray, or white colours with structureless zones are the strongest indicators when differentiating between benign and malignant mucosal lesions in dermoscopy, mainly in older patients.
Easy to be followed, this rule is based on previous research (9) and can be explained by some morphological origins and behaviour of the cells:
- Normal melanocytes are involved in mucosal melanosis and in constitutive hyperpigmentation, as well as keratinocytes.
- Unlike keratinocytes, in melanoma the melanocytes are retained into the epidermis, even if they become mutated and do not show apoptosis.
- The origin of malignant melanocytes in mucosa is uncertain and they invade mucosa and submucosa, without dendritic projections.
- The origin of nevocytes is neural crests and are distributed into the dermis or the dermo-epidermal junction.
|Parallel pattern||The pigmentation is linearly distributed (wispy linear streaks)||Vulvar melanosis, in focal areas of mucosal melanoma, pigmented warts|
|Structureless (homogenous) pattern||Diffuse light to dark brown, black, grey-blue pigmented or white areas devoid of any visible structures. In white structures polymorphic vessels could be visible||Highly suggestive for melanoma, mainly in elderly people|
|Reticular pattern||Honeycomb pattern of pigmented network|
|Dotted globular pattern||Dots and globules||Melanocytic lesions
|Ring-like pattern||Do not form a complete circle (“fish scale like structures”)||Melanosis|
- Blum A, Simionescu O. Mucosal Lesions. In: Marghoob AA, Malvehy J, Braun RP, editors. An Atlas of Dermoscopy, [Internet]. Second Edi. CRC Press Taylor and Francis Group; 2012. p. 301–9. Available from: https://www.crcpress.com/An-Atlas-of-Dermoscopy-Second-Edition/Marghoob-Malvehy-Braun/p/book/9780415458955
- Laguna C, Pitarch G, Roche E, Fortea JM. [Atypical pigmented penile macules]. Actas Dermosifiliogr [Internet]. 2006 Sep [cited 2017 Aug 7];97(7):470–2. Available from: http://www.ncbi.nlm.nih.gov/pubmed/16978549
- de Giorgi V, Massi D, Brunasso G, Salvini C, Mastrolorenzo A, Zuccati G, et al. Eruptive multiple blue nevi of the penis: a clinical dermoscopic pathologic case study. J Cutan Pathol [Internet]. 2004 Feb [cited 2017 Aug 7];31(2):185–8. Available from: http://www.ncbi.nlm.nih.gov/pubmed/14690465
- Hassona Y, Sawair F, Al-karadsheh O, Scully C. Prevalence and clinical features of pigmented oral lesions. Int J Dermatol [Internet]. 2016 Sep [cited 2017 Aug 7];55(9):1005–13. Available from: http://doi.wiley.com/10.1111/ijd.13133
- Ianhez M, Cestari S da CP, Enokihara MY, Seize MB de PM. Dermoscopic patterns of molluscum contagiosum: a study of 211 lesions confirmed by histopathology. An Bras Dermatol [Internet]. [cited 2017 Aug 7];86(1):74–9. Available from: http://www.ncbi.nlm.nih.gov/pubmed/21437525
- Dong H, Shu D, Campbell TM, Frühauf J, Soyer HP, Soyer P, et al. Dermatoscopy of genital warts. J Am Acad Dermatol [Internet]. 2011 May [cited 2017 Aug 7];64(5):859–64. Available from: http://linkinghub.elsevier.com/retrieve/pii/S0190962210003828
- Ronger-Savle S, Julien V, Duru G, Raudrant D, Dalle S, Thomas L. Features of pigmented vulval lesions on dermoscopy. Br J Dermatol [Internet]. 2011 Jan [cited 2017 Aug 7];164(1):54–61. Available from: http://www.ncbi.nlm.nih.gov/pubmed/20846309
- Marcucci C, Sabban EC, Friedman P, Peralta R, Calb I, Cabo H. Dermoscopic findings in bowenoid papulosis: report of two cases. Dermatol Pract Concept [Internet]. 2014 Oct 31 [cited 2017 Aug 7];4(4):61–3. Available from: http://www.derm101.com/dpc/october-2014-volume-4-no.4/dermoscopic-findings-in-bowenoid-papulosis-report-of-two-cases/
- Blum A, Simionescu O, Argenziano G, Braun R, Cabo H, Eichhorn A, et al. Dermoscopy of Pigmented Lesions of the Mucosa and the Mucocutaneous Junction. Arch Dermatol [Internet]. 2011 Oct 1 [cited 2017 May 25];147(10):1181. Available from: http://www.ncbi.nlm.nih.gov/pubmed/21680757
- Tanioka M, Nakagawa Y, Maruta N, Nakanishi G. Pigmented wart due to human papilloma virus type 60 showing parallel ridge pattern in dermoscopy. doi.org [Internet]. John Libbey Eurotext; [cited 2017 Aug 7];19(6):643–4. Available from: http://www.ncbi.nlm.nih.gov/pubmed/19709979
- Blum A, Beck-Zoul U, Held L, Haase S. Dermoscopic appearance of an amelanotic mucosal melanoma. Dermatol Pract Concept. 2016 Oct 31;6(4):23-25. eCollection 2016 Oct. PMID: 27867742