A 57 Year Old Woman with Widespread Scales and Scattered Erosions

Figure 12.1

Scales over the patient’s face, ears and scalp with perioral and periorbital crusts

Figure 12.2

Exfoliative scales covering the patient’s chest

Figure 12.3

Scales over the patient’s legs and feet with dystrophic toe nails

Based on the case description and the photograph, what is your diagnosis?

Pityriasis rubra pilaris

Pemphigus foliaceus

Ichthyosis

IgA pemphigus

Diagnosis

Pemphigus Foliaceus

The patient was diagnosed with pemphigus foliaceus (PF) and immediately hospitalised. Due to her age and concern for an initial possible infection, systemic treatment began with a course of prednisone starting at 25 mg daily for 1 month and, after a normal G6PD, dapsone 50 mg twice daily. The patient responded well with her blisters resolving. However, in February 2011, her haemoglobin dropped to 104 with reticulocyte of 235, consistent with dapsone-induced haemolysis. Hence her dapsone was ceased.

The patient remained stable for 3 months until May 2011, when her PF relapsed and became resistant to treatment. New blisters and erosions developed over her scalp, arms and upper trunk (Fig. 12.2). Her anti-Dsg 1 level was 250 U/ml (normal <20). This relapse coincided with her being started on perindopril by her family doctor, a well-known cause of PF, which was then ceased and changed to metoprolol. Without the dapsone, her PF was a challenge as it did not respond to multiple other treatment modalities over the next 18 months. These treatments included azathioprine 100 mg twice daily, fixed-dose prednisone of up to 70 mg daily (1 mg/kg/day), IVIG infusions monthly and four weekly doses of 375 mg/m² rituximab.

In January 2012, as her PF remained active, further treatment modalities were trialed with minimal response. She was commenced on mycophenolate 750 mg twice daily as an alternative to azathioprine, and methotrexate gradually increased to 17.5 mg daily while her prednisone was tapered. However, her PF remained active despite the above with PDAI (Pemphigus Disease Area Index) activity score of up to 65.

In April 2013, the patient was recommenced on low dose dapsone and her PF improved. Although she previously had haemolysis with dapsone, it was the only medication her PF had responded to. Her dapsone was recommenced at a small dose of 25 mg weekly, gradually increased to five times weekly over the next 6 months. Her haemoglobin and reticulocyte count were monitored fortnightly, which remained stable. With a combination of dapsone, IVIG infusions, tapered prednisone, mycophenalate and methotrexate, her lesions finally reduced in severity and quantity by end of 2013. Eventually her PF was in remission, and was maintained on dapsone 25 mg five times weekly, tapered prednisone decreased to 6 mg daily and IVIG infusions monthly. Her anti dsg1 ELISA is now 150 U/ml with PDAI of 16.

Discussion

Pemphigus foliaceus (PF) is an acquired autoimmune blistering disease, and accounts for approximately 10 % of all cases of the pemphigus group but may vary in some countries which have an endemic form of PF [8]. It is characterised by the immune system producing auto-antibodies of mainly IgG4 subclass that target the intercellular adhesion glycoprotein desmoglein 1 (Dsg 1). The main two subtypes of PF are idiopathic PF, which is found universally and occurs sporadically, and endemic PF known as fogo selvagem, which occurs in certain geographical areas.

The diagnosis of PF requires three criteria: clinical presentation, histopathology and the presence of auto-antibodies as detected by either direct immunofluorescence (DIF) or indirect immunofluorescence (IIF). Regarding its clinical presentation, PF commonly begin on the trunk, before spreading. Its primary lesions are flaccid, superficial blisters which easily rupture and hence are often missed by clinicians. Commonly, only secondary lesions such as erosions and crusts are observed. The severest form of PF can produce an exfoliative erythroderma. It typically does not affect mucosal surfaces including the oral cavity. It is important to be aware that early PF may mimic various other scaly conditions, causing delays of up to years in making the correct diagnosis. Clinicians should always enquire about the primary lesions in scaly and erosive diseases to try illicit the history of blistering which is not always possible. As our patient did not recall a history of blisters, she was initially misdiagnosed as eczema. Other differential diagnoses of PF include drug eruptions, IgA pemphigus, lupus erythematosus, ichthyosis, psoriasis, pityriasis rubra pilaris and Darier’s disease.

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