Complications
As a source of light, photodynamic therapy can induce or aggravate diseases such as SLE, polymorphous light eruption, actinic prurigo, chronic actinic dermatitis, dermatomyositis, lichen planus actinicus, photodermatitis, phytophotodermatitis, phototoxic drug reactions, photoallergic reactions, and photocontact dermatitis.[147]
However, photodynamic therapy is well tolerated by patients in general. Adverse effects include transient mild-to-moderate pain, irritation, and erythema.
Pruritus may lead to skin breaks from scratching.
Pruritus may lead to skin breaks from scratching, increasing the risk of secondary infection.
Sunlight or any other source of light (e.g., tanning beds) can potentially activate aminolevulinic acid and produce excessive amounts of the photosensitizer protoporphyrin IX.
Protoporphyrin IX is a porphyrin that accumulates and aggravates patients with porphyrias.[146]
Patients with the aspirin (Samter) triad should use diclofenac with caution.[2]
It is recommended that sun exposure is avoided while receiving this therapy.[2]
This is an anticipated reaction of the drugs; can lead to nonadherence. Cycle therapy with rest periods suggested if transient irritation occurs.[2][103]
Adverse effects, most of them expected, include burning, crusting, allergic contact dermatitis, erosions, erythema, hyperpigmentation, irritation, pain, photosensitivity, pruritus, scarring, rash, soreness, and ulceration.[118]
The progression of AKs to invasive squamous cell carcinoma (SCC) is a continuum in which Bowen disease (SCC in situ) represents the midpoint between the two conditions.
Atypical keratinocytes have not invaded through the basement membrane of the dermoepidermal junction.
Although all lesions of Bowen disease have the potential to progress to invasive SCC if not treated, the risk of progression has been calculated as being from 3% to 5%.[143]
Invasive SCC is the second most common skin cancer, with approximately 200,000 new diagnoses each year, and between 1300 and 2300 deaths from nonmelanoma skin cancer, mostly metastatic SCC, in the US.[41]
All AKs have the potential to progress to invasive SCC if not treated.
The progression has been calculated as being between 0.025% and 16% per year, with one report showing 20% per year.[126][127] In older adults with a history of multiple keratinocyte carcinomas, risk of progression is 0.60% at 1 year and 2.57% at 4 years.[128]
The metastatic risk has been reported to be between insignificant and 40%, although the 5-year metastasis rate of between 2% and 6% is the most widely accepted figure.[3][13][144][145]
Leukocytosis is the most frequent hematologic adverse effect.
Less frequent: emotional upset, insomnia, irritability, medicinal taste, stomatitis, eosinophilia, thrombocytopenia, and toxic granulation.[103]
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