Approach

A history of sun and ultraviolet (UV) exposure may be observed as sun-damaged skin. Ask patients about their history of UV exposure; questioning about X-ray and arsenic exposure is advised.

A medical history of xeroderma pigmentosum, nevoid basal cell carcinoma (Gorlin-Goltz) syndrome, or transplantation (particularly solid organ) significantly increases risk for basal cell carcinoma (BCC).[31][32][40]

Skin examination

Perform a thorough skin examination; use good lighting and possibly handheld lenses or a dermoscope.[42][43]​ Undertake a full skin (whole body) examination for all patients with confirmed BCC, and consider performing one at initial presentation, especially if history or clinical evidence suggests a higher risk of skin cancer. People with BCC have an increased risk of developing other skin tumours (both keratinocyte carcinomas and melanoma), and patients may present with additional, concurrent precancers or cancers at other sites.[44][45]

Recognition of different types of BCC is essential, as the therapy will vary according to type.

[Figure caption and citation for the preceding image starts]: Nodular basal cell carcinoma on the cheek, on background of diffuse solar damage with marked solar elastosisFrom the collection of Prof. Robert A. Schwartz [Citation ends].com.bmj.content.model.Caption@76896734[Figure caption and citation for the preceding image starts]: Superficial BCC: A plaque somewhat translucent with focal crusting and ulceration, enlarging with a nodular qualityFrom the personal collection of Prof. Robert A. Schwartz; used with permission [Citation ends].com.bmj.content.model.Caption@37700b3c[Figure caption and citation for the preceding image starts]: Digital dermoscopy image of above superficial basal cell carcinoma utilizing Sklip PRO dermatoscopeFrom the personal collection of Prof. Robert A. Schwartz; used with permission [Citation ends].com.bmj.content.model.Caption@1d047ee6

Seek the following characteristics of BCC:[3][4][45]

  • Pearly papules and/or plaques

  • Non-healing scabs

  • Small crusts and non-healing wounds

  • Plaques, nodules, and tumours with rolled borders

  • Papules with associated telangiectasias.

Additionally, stretching skin under a good light source (the 'stretch test') will accentuate the pearly nature of the tumour and has been shown to improve diagnostic accuracy.[42][46]

Biopsy

Either a shave biopsy or punch biopsy, depending on size and location of tumour, can be performed.​​[42][44][45]​​​[47]​​​​ Deep reticular dermis should be included in the biopsy to avoid missing an infiltrative histology, which may sometimes be present only at the deeper, advancing margins of a tumour.[44]

A punch biopsy is best used in cosmetically non-challenging areas, as it requires closure with stitches. An advantage of punch biopsy is that the tools may be available in sizes of up to 12 mm, and therefore lesions smaller than this can be removed in a single procedure, facilitating simultaneous diagnosis and treatment.[48]

Reserve a shave biopsy for cosmetically challenging areas such as the face.

Dermatohistopathology

The histopathological diagnosis of BCC is often straightforward. Occasionally, distinction from other neoplasms, such as a trichoepithelioma, may be challenging. A BCC manifests dermal masses of varying sizes and shapes composed of uniform basophilic cells with large oval nuclei and scant cytoplasm. These masses are often tightly associated with epidermis or a follicular opening, and have a peripheral cell layer demonstrating a palisading pattern of nuclei.[3][4][5][Figure caption and citation for the preceding image starts]: Histological appearance of basal cell carcinoma (20x, H-E stain); characteristic peripheral nuclear palisading, stroma-epithelium split, and so-called mucinous nature of the stroma are seenFrom the collection of Drazen M. Jukic, MD, PhD [Citation ends].com.bmj.content.model.Caption@51a56c33

BCC is one of the human neoplasias with the highest mitotic rate (high mitotic activity), but it also has a high apoptotic rate. Thus, the neoplasm is overall slow-growing, and both features (mitotic and apoptotic figures) are used as one of the distinguishing criteria for diagnosis of BCC. In a small percentage, BCCs are pigmented and might resemble a melanoma clinically.[3][4]

Imaging for high risk or advanced disease

Consider magnetic resonance imaging (MRI) or computed tomography (CT) for:[44]

  • Patients with high-risk BCC if clinical examination is insufficient for determining disease extent

  • Locally advanced disease

Imaging studies are also indicated in rare instances where patients present with metastatic BCC.[44]

Choice of imaging modality and targeted area depends on the suspected extent of disease after multidisciplinary discussion.[44][45] MRI may be preferred for suspected perineural invasion or to gauge the extent of local disease. CT may be preferred for suspected bone involvement or to confirm and gauge the extent of nodal or distant metastasis.[44] 

Patients with low-risk BCC do not require imaging.[44][45] For details on risk stratification, see Criteria.

Emerging tests

In vivo multiphoton microscopy uses non-invasive, label-free, in vivo imaging to reveal several characteristic features of BCC lesions that may help facilitate diagnosis.[49] Reflectance confocal microscopic technologies have become a popular method for non-invasive approaches to aid in the diagnosis of basal cell carcinomas.[45][50][51]​​​​ Adding artificial intelligence to non-invasive imaging has tremendous potential and is the subject of active investigation.[50] However, further research is needed to isolate pooled diagnostic accuracy.[50]

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