What is the relationship between epidermoid cyst and squamous cell carcinoma?

From the Guidelines

Epidermoid cysts and carcinomas are distinct skin conditions that require different management approaches, with epidermoid cysts being benign and carcinomas being malignant, thus requiring prompt treatment to prevent morbidity and mortality. Epidermoid cysts are slow-growing, dome-shaped lesions containing keratin debris within a sac lined by stratified squamous epithelium, typically appearing on the face, neck, trunk, and genitals, and usually don't require treatment unless they become infected, painful, or cosmetically bothersome 1. In contrast, cutaneous carcinomas, including basal cell and squamous cell carcinomas, are malignant skin cancers that require prompt treatment, with management depending on the type, location, and stage, and options including surgical excision with appropriate margins, Mohs micrographic surgery, radiation therapy, topical medications, or systemic therapy for advanced cases 1.

Key Considerations

• Epidermoid cysts rarely transform into malignancies, but any rapid growth, ulceration, bleeding, or color change in a previously stable cyst warrants immediate evaluation to rule out malignant transformation or misdiagnosis of a primary skin cancer 1.
• Patients with certain subtypes of epidermolysis bullosa, such as recessive dystrophic EB, have a high risk of developing squamous cell carcinomas, which are aggressive and can lead to significant morbidity and mortality, thus requiring regular skin checks and clinical surveillance 1.
• The management of cutaneous squamous cell carcinoma in patients with epidermolysis bullosa involves a multidisciplinary approach, with surgical excision being the standard treatment, and the choice of surgical technique and wound closure method depending on the site and size of the primary tumor, as well as the patient's functionality and ability to carry out activities of daily living 1.

Management Approach

• Surgical excision with appropriate margins is the recommended treatment for cutaneous squamous cell carcinomas, with the goal of complete removal or destruction of the primary tumor and any metastases 1.
• Regular skin checks and clinical surveillance are essential for early detection and treatment of squamous cell carcinomas in patients with epidermolysis bullosa, with a high index of suspicion for atypical wounds and a low threshold for biopsy or further evaluation 1.
• The management of epidermoid cysts and carcinomas should prioritize morbidity, mortality, and quality of life, with a focus on prompt treatment and regular follow-up to prevent complications and improve outcomes 1.

From the Research

Epidermoid Cyst and Carcinoma

• Epidermoid cysts are common benign skin lesions that can occur anywhere on the body, and malignant transformation into squamous cell carcinoma is rare 2, 3, 4, 5.
• The exact pathophysiology of malignant transformation is still poorly understood due to its scarcity 2.
• Clinical presentation of epidermoid cysts is variable, leading to some differential diagnoses, and diagnosis needs histopathological confirmation 6.
• Treatment of choice for epidermoid cysts is surgery, and it is crucial to remove the cyst wall completely to avoid relapses 6, 3.
• Routine excision of all epidermal cysts is not recommended, instead, excision and pathology should be performed for symptomatic epidermoid cysts, or those that rapidly grow, or do not respond to medical therapy 3.
• Histological examination is important in the diagnosis of malignant transformation, as it may not be suspected until histological examination reveals it 2, 5.
• The prevalence of malignant transformation of epidermoid cysts into squamous cell carcinoma is low, with only a few cases reported in the literature 2, 3, 4, 5.