The Efficacy of Using Oral Sodium Cromoglycate for Controlling Epidermolysis Bullosa‐Related Pruritus

Epidermolysis Bullosa (EB) is a rare inherited multisystem disorder that currently lacks a definitive treatment [1]. Therapeutic options for EB are limited, with the primary focus on symptom control. Pruritus is a common symptom in EB patients, with substantial differences across the subtypes (EB Simplex 74%, Junctional EB 100%, Dystrophic EB 93%) [1]. Sodium cromoglycate, widely used in its inhaled form for bronchial asthma and in its oral form for treating mastocytosis in children, is effective due to its mast cell stabilisation properties [2]. We previously published a case series of mild bullous pemphigoid patients who responded well to sodium cromoglycate [3]. Here, we present two cases of patients with EB-induced pruritus managed with oral sodium cromoglycate. The first patient is a 41-year-old Caucasian female with dominant dystrophic EB (DDEB) due to a missense variant c.6182G>T in the COL7A1 gene. She had persistent pruritus of her back, arms, and legs. At baseline, her validated EB disease Activity and Scarring index (EBDASI) score was 6 for activity and 35 for damage, and her quality of life in epidermolysis bullosa (QoLEB) was 12/51. For her EB-induced pruritus, she was commenced on oral sodium cromoglycate 100 mg once daily and followed up after 6 months. The second patient is an 18-year-old Caucasian male with extensive recessive dystrophic EB (RDEB) due to heterozygous variants in the COL7A1 gene (c.1452-1453del and c.6329dup) affecting most of his back, chest, and bilateral upper and lower limbs. He also had anonychia of most of his fingers and toes. Additionally, he had severe EB-induced pruritus for which he had been utilising regular promethazine with no adequate control. At baseline, his EBDASI was 35 for activity and 96 for damage, and his Dermatology Life Quality Index (DLQI) was 12/30. He was, therefore, started on oral sodium cromoglycate 100 mg once daily and followed up after 6 months. At six-month follow up, both patients reported an improvement in their itch symptoms; however, it did not contribute significantly to wound healing during this period. The first patient's EBDASI showed a reduction in activity score from 6 to 2 and her QoLEB score was 11 after 6 months of treatment (Figures 1 and 2), while the second patient's EBDASI showed a mild reduction in activity score from 35 to 31, and his DLQI significantly reduced from 12 at baseline to 2 after 6 months (Figures 1 and 2). He also described a reduction in the need for adjuvant promethazine 25 mg nocte from once or twice weekly to once or twice monthly. The use of oral sodium cromoglycate for reduction in pruritus in inherited EB has not yet been described. In Australia, this medication is compounded as a powder in a capsule form, which makes it convenient for EB patients with swallowing difficulty to have the powder mixed into food or liquids. Reducing pruritus is an unmet need and a top priority for patients with EB as this allows trauma to be minimised, and accordingly less bullae formation. Sodium cromoglycate has many other applications in Dermatology, namely in mastocytosis [2], bullous pemphigoid [3] and atopic dermatitis [4]. It has been demonstrated through tryptase immunostaining that biopsies of skin in patients with RDEB contain significantly more mast cells than control skin, which explains why this medication holds promise for this disease [5]; however, further prospective randomised controlled trials are required to better assess its efficacy. Australasian Blistering Diseases Foundation. Open access publishing facilitated by University of New South Wales, as part of the Wiley - University of New South Wales agreement via the Council of Australian University Librarians. The patients discussed in this manuscript have given written informed consent to the publication of their medical photographs. The authors declare no conflicts of interest. The data that support the findings of this study are available from the corresponding author upon reasonable request.