Basal cell carcinoma
In this chapter we describe the dermoscopy features of basal cell carcinoma
It has the following subchapters:
Basal cell carcinoma (BCC) is the most common type of skin cancer in the world. Although mortality related to BCC is negligible, BCCs can be associated with significant morbidity, especially if left untreated and/or if discovered when they have attained relatively large diameters. Clinically, BCC can present with a variety of morphologies ranging from erythematous patches to ulcerated nodules. There are multiple histopathologic subtypes of BCC including superficial, nodular, morpheaform/sclerosing/infiltrative, fibroepithelioma of Pinkus, microcytic adnexal and baso-squamous cell BCC. Each subtype can be clinically pigmented or non-pigmented. It is not uncommon for BCCs to display pigment on dermoscopy with up to 30% of clinically non-pigmented BCCs revealing pigment on dermoscopy . Based on the degree of pigmentation, some BCCs can mimic melanomas or other pigmented skin lesions . Depending on the subtype of BCC and the degree of pigmentation, the clinical differential diagnosis can be quite broad ranging from benign inflammatory lesions to melanoma. Fortunately, the use of dermoscopy has dramatically improved the diagnostic accuracy and diagnostic confidence of clinicians for both pigmented and non-pigmented BCCs (Schematics show the features seen in pigmented and non-pigmented BCC). In addition, dermoscopy permits for the diagnosis of clinically tiny BCCs since the dermoscopic criteria for BCC are visible irrespective of the size of the tumor .
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Both the negative and the positive dermoscopic features associated with pigmented BCCs have been well characterized . The negative feature of pigmented BCCs is that they cannot display any structures seen in melanocytic lesions including pigment network, streaks, negative network, aggregated or peripheral brown globules. The positive features of pigmented BCC include the presence of any one of the following structures:
Large blue-gray ovoid nests:
The nests are defined as confluent or nearly confluent, well-circumscribed, pigmented ovoid areas. The difference between an ovoid nest and a blue-gray globule is the relative size of the structure. An ovoid nest encompasses at least 10% of the surface area of the lesion and blue-gray globules are smaller. The presence of an ovoid nest corresponds to basal cell tumor islands in the dermis and these lesions will prove to be nodular BCC on histopathology.
Multiple blue-gray dots and globules:
Blue-gray dots are pinpoint blue-gray structures that are often distributed in a buckshot scatter like pattern (Figure ). This structure can be seen in early nodular BCC or in superficial BCC. Blue-gray globules are well-defined round or oval structures, larger than dots, but smaller than large ovoid nests. They are not aggregated as would be seen in melanocytic lesions. They usually have a blue-gray color; however, depending on the location within the dermis (Tyndall effect) and degree of melanin within the pigmented basaloid tumor islands, the globules can appear brown or pink in color. This structure corresponds to small basal cell tumor islands in the dermis and thus they will prove to be nodular BCC on histopathology.
These areas are defined as discrete, linear to bulbous extensions connected at an off-center base area, forming a leaf-like pattern. They are usually brown or gray-blue in color (Figure ). This structure is quite specific for superficial BCC. The bulbous to linear extensions forming the leaf can sometimes be mistaken for streaks seen in melanoma. However, the streaks in melanoma tend to be discrete, well-delineated, narrow, relatively in-focus linear extensions that are located at the perimeter of the lesion and are directly connected to the main pigmented tumor mass. Streaks in melanoma always radiate in a direction pointing away from the main pigmented tumor mass and they radiate toward normal skin. In addition, streaks in a melanoma appear to converge towards the geometric center of the lesion, which is often hyperpigmented and has a blue-white veil. In contrast, extensions seen in leaf-like structures tend to be broader and often appear “fuzzy” or out of focus. They do not have to be located at the lesion’s perimeter and they do not always have to radiate away from the main tumor mass toward normal skin. In addition, the extensions seen in BCC tend to converge at an off center pigmented base. This base together with its “extensions” is present focally and most often located towards the periphery of the tumor and it is this configuration that creates the leaf-like structure. In addition, the geometric center of BCCs manifesting “fuzzy streaks” (leaf-like areas) is often hypopigmented and relatively structureless.
These are radial projections that surround a central darker point. This is similar to leaf-like structures described above but instead of having the radial projections converging at an off-center base they radiate around a central base. The projections have a tan, blue, or gray color, and the central point or hub is usually dark brown, blue, or black (Figure ). At times the radial projections are not well defined and the spoke-wheel-like structure appears as a brownish round ill marginated globule that has a central darker hub; this particular patterned structure is called the ‘’’concentric structure’’’ or ‘’’concentric globule’’’. (Figure ). The spoke-wheel-like structure (including the concentric structure) is highly specific for superficial BCCs.
These consist of multiple branching blood vessels in a tree-like pattern. The base of the vessel is larger and the branches of the vessel become smaller in diameter. The vessels tend to be bright red and sharply in focus. Arborizing vessels surround dermal basal cell tumor islands and thus are associated with nodular BCC.
These structures consist of shallow erosions that may be covered with congealed blood. They can also appear to have an orange hue if covered with a serous crust. Ulcers covering at least 10% of the surface area of the BCC correspond with nodular BCC. The presence of multiple smaller ulcers, termed erosions, is a feature seen in superficial BCC.
Shiny white blotches and strands:
This structure can only be seen with polarized dermoscopy and consists of white patches or blotches and linear white areas called strands .
- Lallas et al.: Dermoscopy uncovers clinically undetectable pigmentation in basal cell carcinoma. Br. J. Dermatol. 2014;170:192-5. PMID: 24117444. DOI.
- Bakos et al.: Radial streaking: unusual dermoscopic pattern in pigmented superficial basal cell carcinoma. J Eur Acad Dermatol Venereol 2007;21:1263-5. PMID: 17894724. DOI.
- Altamura et al.: Dermatoscopy of basal cell carcinoma: morphologic variability of global and local features and accuracy of diagnosis. J. Am. Acad. Dermatol. 2010;62:67-75. PMID: 19828209. DOI.
- Popadić & Vukićević: What is the impact of tumour size on dermoscopic diagnosis of BCC?. J Eur Acad Dermatol Venereol 2015;29:2474-8. PMID: 25358026. DOI.
- Menzies: Dermoscopy of pigmented basal cell carcinoma. Clin. Dermatol. 2002;20:268-9. PMID: 12074864.
- Menzies et al.: Surface microscopy of pigmented basal cell carcinoma. Arch Dermatol 2000;136:1012-6. PMID: 10926737.
- Navarrete-Dechent et al.: Association of Shiny White Blotches and Strands With Nonpigmented Basal Cell Carcinoma: Evaluation of an Additional Dermoscopic Diagnostic Criterion. JAMA Dermatol 2016;152:546-52. PMID: 26792406. DOI.