Aberrant basal-cell carcinoma

= Aberrant Basal-Cell Carcinoma =

Basal-cell carcinoma (BCC) is the most common form of skin cancer, typically arising from the basal cells in the epidermis. However, aberrant basal-cell carcinoma refers to cases where the carcinoma exhibits unusual characteristics, such as atypical locations, histological features, or behavior. Understanding these aberrant forms is crucial for accurate diagnosis and effective treatment.

Epidemiology

Basal-cell carcinoma is the most prevalent cancer in humans, with millions of cases diagnosed annually worldwide. Aberrant BCCs are less common but are significant due to their atypical presentation. They may occur in younger patients, in unusual locations, or exhibit aggressive behavior not typical of standard BCCs.

Etiology

The primary risk factor for basal-cell carcinoma is ultraviolet (UV) radiation from sun exposure. However, aberrant BCCs may also be influenced by genetic factors, such as mutations in the PTCH1 gene, or environmental factors, such as exposure to carcinogens. Immunosuppression and previous radiation therapy are also known risk factors.

Clinical Presentation

Aberrant BCCs can present in various ways:

• Unusual Locations: While typical BCCs are found on sun-exposed areas like the face and neck, aberrant BCCs may appear on non-sun-exposed areas such as the trunk, limbs, or even the genital region.
• Atypical Appearance: These carcinomas may not exhibit the classic pearly nodules or telangiectasia. Instead, they might present as pigmented lesions, ulcerated plaques, or mimic other skin conditions.
• Aggressive Behavior: Some aberrant BCCs may grow rapidly, invade deeper tissues, or metastasize, which is rare for typical BCCs.

Histopathology

Histologically, aberrant BCCs may show unusual features such as:

• Infiltrative Growth Patterns: More aggressive and invasive growth patterns compared to nodular or superficial BCCs.
• Basosquamous Differentiation: Areas of squamous differentiation within the tumor, which can indicate a more aggressive behavior.
• Pigmentation: Increased melanin production leading to pigmented BCCs, which can be confused with melanoma.

Diagnosis

Diagnosis of aberrant BCC involves a combination of clinical examination, dermoscopy, and histopathological analysis. Biopsy is essential to confirm the diagnosis and to differentiate it from other skin malignancies such as squamous cell carcinoma or melanoma.

Treatment

Treatment options for aberrant BCCs are similar to those for typical BCCs but may require more aggressive approaches due to their atypical nature:

• Surgical Excision: The primary treatment for most BCCs, ensuring clear margins to prevent recurrence.
• Mohs Micrographic Surgery: Particularly useful for BCCs in cosmetically sensitive areas or those with aggressive features.
• Radiation Therapy: An option for patients who are not surgical candidates.
• Targeted Therapy: Vismodegib and sonidegib are hedgehog pathway inhibitors used for advanced BCCs.

Prognosis

The prognosis for aberrant BCCs varies depending on the location, size, and histological features of the tumor. Early detection and treatment are crucial for a favorable outcome. Regular follow-up is recommended to monitor for recurrence or new lesions.

Conclusion

Aberrant basal-cell carcinoma represents a challenging subset of BCCs due to their atypical presentation and potential for aggressive behavior. Awareness and understanding of these variants are essential for dermatologists and oncologists to ensure accurate diagnosis and effective management.

References

• National Cancer Institute. "Basal Cell Carcinoma Treatment (PDQ®)–Patient Version." Accessed October 2023.
• Skin Cancer Foundation. "Basal Cell Carcinoma." Accessed October 2023.
• Rubin AI, Chen EH, Ratner D. "Basal-Cell Carcinoma." New England Journal of Medicine, 2005.