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

Careful examination of the whole skin (whole-body examination) should be undertaken in patients with clinical evidence or a history of considerable sun exposure.​[43][44] Use good lighting and possibly handheld lenses.[42][45][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@5592ca4c Recognition of different types of BCC is essential, as the therapy and follow-up will vary according to type.

[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@370daaef[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@29b872fb

Seek the following characteristics of BCC:[3][4][46]

  • Pearly papules and/or plaques[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@6b855b00

  • 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][47]

Biopsy

Either a shave biopsy or punch biopsy, depending on size and location of tumour, can be performed.​​[42][44][46]​​[48]​​​​

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.[49]

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@5c8be3c0

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]

Emerging investigations

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.[50] Dermatoscopic and reflectance confocal microscopic technologies have become a popular method for non-invasive approaches to aid in the diagnosis of basal cell carcinomas.[46][51][52]​​​​ Adding artificial intelligence to non-invasive imaging has tremendous potential and is the subject of active investigation.[51] However, further research is needed to isolate pooled diagnostic accuracy.[51]

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