Insights Into Photdermatoses: Diagnosis and Treatment Updates

During his session, “Photodermatoses: Diagnosis and Management,” Henry W. Lim, MD, presented the various dermatoses, and how to recognize important and new developments in photodermatoses.

To start, he listed the following dermatoses to review and offer insights on:

• Polymorphous light eruption (PMLE)
• Actinic prurigo (AP)
• Hydroa vacciniforme (HV)
• Chronic actinic dermatitis (CAD)
• Solar urticaria (SU)/solar angioedema
• Drug-induced photosensitivity
• Erythropoietic protoporphyria (EPP)

In patients with lighter skin, PMLE typically presents as mildly pruritic erythematous or urticarial papules on skin exposed to the sun within a few hours of exposure. In patients with darker skin tones, PMLE can present as a pinhead papular eruption, which looks more like “goose pimples.” Patients with PMLE are more resistant to UV-induced immunosuppression. Dr Lim shared that the treatment options available include encouraging patients to seek shade, broad-spectrum sunscreens, NB-UVB hardening, oral corticosteroids, hydroxychloroquine (5 mg/kg/day), azathioprine (2–2.5 mg/kg/day), and possibly polypodium leucotomos (480–1200 mg/day).

Next, Dr Lim addressed AP, which is characterized by excoriation/scars, cheilitis and conjunctivitis, involvement of covered sites, eruption in winter, and lesions lasting more than 4 weeks. The treatments he discussed include photoprotection, suggesting patients move to lower altitudes if possible, topical and oral corticosteroids, NB-UVB or psoralen ultraviolet A (PUVA), dupilumab, and thalidomide (100–200 mg/day).

He continued with HV, sharing that classic HV characteristics include:

• Childhood onset
• Papulovesicles on sun-exposed areas
• Typically resolves by early adulthood
• Decreased MED-A, rarely decreased MED-B
• Association with Epstein-Barr virus (EBV) has been reported
• Positive provocative test with UVA

Treatment options include hydroxychloroquine, UVB, and PUVA. Dr Lim also added that there is an HV-like lymphoproliferative disorder commonly seen in Asia and Latin America, which has the follow traits:

• Papulovesicles on sun-exposed and sun-protected areas
• Facial edema, fever, lymphadenopathy, ocular and mucosal lesions, hepatosplenomegaly, vasculitis, and panniculitis
• Action spectrum: UVA
• Possible progression to EBV-associated systemic T-cell or natural killer-cell lymphoma

Then Dr Lim presented CAD, with diagnostic criteria that include chronic photodermatitis, low phototest results (to UVA and/or UVB and/or visible light), histology such as dermal lymphohistiocytic infiltrate and/or +/- epidermal spongiosis, and +/- atypical mononuclear cells. CAD treatment options consist of sunscreen/photoprotection, topical tacrolimus, mycophenolate mofetil, dupilumab, cyclosporine, azathioprine, oral corticosteroids (for flares), NB-UVB hardening (with oral prednisone), hydroxychloroquine, and apremilast.

Next, SU/solar angioedema was discussed, with Dr Lim stressing various therapeutic options for its treatment, including antihistamines, UVA (or UVA1), cyclosporine (3–5 mg/kg), intravenous immunoglobulin (400 mg/kg/day x 5 days = 2 gm/kg), and omalizumab.

He continued with drug-induced photosensitivity, sharing that recent strong evidence was supportive of the medications used as treatment, such as vemurafenib (BRAF inhibitor for metastatic melanoma), nonsteroidal anti-inflammatory drugs, and antibiotics (fluoroquinolones, tetracyclines).

Finally, Dr Lim showcased EPP, noting that afamelanotide is still the most effective treatment. Afamelanotide is a potent analogue of human alpha-melanocyte, leading to stimulating hormone that binds to the melanocortin 1 receptor to induce production of eumelanin. In fact, the melanogenesis may provide a major antioxidant defense in melanocytes. He noted that the use of afamelanotide as a subcutaneous monthly implant when following sun exposure had a longer pain-free time duration and patients have reported improved quality of life. He also shared the common adverse effects, which include headaches, nausea, nasopharyngitis, and back pain.

“The take-home message is that key aspects for [diagnosing] photodermatoses [are] looking at the onset of eruption after sun exposure, morphology, and distribution of lesions,” he concluded.

Reference
Lim HW. Photosensitivity: diagnosis and management. Presented at: Dermatology Week 2022; September 14-17, 2022; Virtual.