Guttate psoriasis

Guttate psoriasis most commonly presents in children and young adults, classically appearing 2–3 weeks after a group A streptococcal pharyngitis infection (Menter et al. 2009). Other less commonly associated triggers include viral infections and medications (Fry and Baker 2007). Guttate psoriasis may arise as an initial manifestation or acute exacerbation in chronic plaque psoriasis. The guttate lesions are frequently described as small, teardrop-shaped erythematous, scaly, sharply demarcated papules. Most commonly they are numerous and diffusely distributed along the trunk and proximal extremities. The differential diagnosis can include small plaque parapsoriasis, pityriasis rosea, pityriasis lichenoides chronica, secondary syphilis, tinea corporis, and pemphigus foliaceus.

Fortunately, guttate psoriasis tends to have a good prognosis with complete resolution and low rates of recurrence. Several small-scale retrospective studies have investigated the long-term outcomes of patients who developed guttate psoriasis. Of the patients with a single manifestation of guttate psoriasis, 25–39% of patients progressed to a chronic form of psoriasis (Ko et al. 2010; Pfingstler et al. 2016). The role of antistreptococcal antibiotics is unclear; however, studies do not advocate the empiric use of antibiotics (Dogan et al. 2008). Tonsillectomy has also been reported to improve outcomes for recurrent and recalcitrant cases; however, direct evidence is lacking (Owen et al. 2000).

Ultraviolet B (UVB) phototherapy is indicated as a first-line treatment of generalized guttate psoriasis. Narrowband UVB (NB-UVB) is the phototherapy of choice due to its superior efficacy and minimal side effects compared to other modalities such as broadband UVB and ultraviolet A phototherapy (Barbagallo et al. 2001). Additionally, the lack of systemic toxicity makes phototherapy a more appealing management option when compared to systemic treatments. Recalcitrant lesions may demonstrate better response with the concomitant use of topical corticosteroids or vitamin D analogs. However, patients with more widespread skin involvement may find the use of topical treatments challenging and cumbersome.

Methotrexate is a well-established medication in the management of various forms of psoriasis and is also considered to be a first-line agent in the treatment of guttate psoriasis. The most common reported side effects are nausea, dyspepsia, anorexia, and headache. Gastrointestinal side effects can be minimized with folic acid supplementation without decreasing therapeutic efficacy (Shea et al. 2013). Due to the possibility of developing serious side effects such as bone marrow suppression and hepatic fibrosis or cirrhosis, pretreatment laboratory studies are recommended. Testing should place an emphasis on blood cell count, hepatic, and kidney function. In the case of our patient, pre-therapy laboratory studies revealed mild transaminitis. Although mildly abnormal liver function tests are not considered to be an absolute contraindication, we felt that the potential risks outweighed the benefits of therapy, especially with other modalities such as NB-UVB phototherapy as an excellent and safe alternative.