From the Guidelines
Porokeratosis is a rare skin disorder characterized by abnormal keratinization, resulting in distinctive skin lesions with raised borders, and its treatment can include topical photodynamic therapy, as suggested by a case series of disseminated superficial actinic porokeratoses treated with ALA-PDT or MAL-PDT, showing initial response and marked improvement in some cases 1. The condition typically appears as round or irregularly shaped patches with a ridge-like border called a "cornoid lamella," which is a column of parakeratotic cells visible under microscopic examination.
- The clinical variants of porokeratosis include:
- Disseminated superficial actinic porokeratosis (DSAP)
- Linear porokeratosis
- Porokeratosis of Mibelli
- Punctate porokeratosis
- The condition is believed to result from abnormal clonal expansion of keratinocytes with genetic mutations, often triggered by ultraviolet radiation, immunosuppression, or genetic predisposition, as seen in other skin disorders treated with photodynamic therapy, such as actinic cheilitis, which showed complete clearance and good cosmesis in some cases 1. While porokeratosis is generally benign, there is a small risk of malignant transformation to squamous cell carcinoma within the lesions, particularly in long-standing cases.
- Treatment options include:
- Topical retinoids
- 5-fluorouracil
- Imiquimod
- Cryotherapy
- Laser therapy
- Surgical excision
- Topical photodynamic therapy, as shown in the study 1, which can be an effective treatment for some cases of porokeratosis. Sun protection is essential for patients with porokeratosis, as UV exposure can worsen the condition and potentially increase the risk of malignant transformation.
From the Research
Definition and Characteristics of Porokeratosis
- Porokeratosis (PK) is a rare skin disease of unknown etiology, characterized by a keratinization disorder that may appear in several clinical forms and can undergo malignant transformation 2.
- It is a group of skin diseases characterized by abnormal keratinization, which may have a genetic background and can be triggered by environmental factors, including UV exposure and infections 3.
- Porokeratosis comprises a group of heterogeneous and uncommon acquired or congenital skin diseases of unknown origin, characterized by a keratinization disorder resulting from abnormal clonal expansion of keratinocytes 4.
Clinical Manifestations and Diagnosis
- Clinical manifestations of porokeratosis are variable, with localized, disseminated, and even eruptive forms 4.
- Diagnosis is established based on clinical and histopathological examination, dermatoscopy, and reflectance confocal microscopy 3.
- The histopathological hallmark of PK is the cornoid lamella 2.
Treatment Options
- Various treatment options are available, including topical combination therapy with cholesterol and statins, topical retinoids, cryotherapy, laser therapy, and surgical excision of lesions, but none are fully effective 3.
- Porokeratosis of Mibelli showed the best outcomes after treatment with imiquimod cream and linear PK responded well to topical or systemic retinoids 2.
- Topical vitamin D acid derivatives may be the best therapeutic option for disseminated PK 2.
- Newer modalities of therapy such as photodynamic therapy, ingenol mebutate, and HMGCoA inhibitors may play a role in the future 5.
Prognosis and Complications
- Porokeratosis has been associated with immunosuppression, ultraviolet radiation, and systemic, infectious, and neoplastic diseases 4.
- Many authors consider it to be a premalignant condition because of the potential for malignant transformation to squamous cell or basal cell carcinoma 4.
- Development of malignancy in a few variants is a concern, with linear, disseminated superficial actinic, and giant lesions being most prone to developing malignancies 5.