Cutaneous lupus erythematosus is an autoimmune disease which encompasses a group of clinical entities: localised and generalised discoid lupus erythematosus (DLE), exfoliative cutaneous lupus erythematosus (ECLE), mucocutaneous lupus erythematosus (MCLE) and vesicular cutaneous lupus erythematosus (VCLE). These conditions are uncommon to rare and all require long-term treatment, often with drugs which can have serious adverse effects. Evidence-based treatment and management described in the literature is lacking for some forms of the disease. This article gives an overview of the different variants and the treatment and management options.
Discoid lupus erythematosus, also referred to as facial lupus erythematosus
Of all the variants, DLE is probably the one more frequently encountered in general practice. Generally, the lesions are confined to the nasal planum and the bridge of the nose. The condition is mainly seen in dolichocephalic breeds like the German Shorthaired Pointer (GSP), German Shepherd Dogs, Collies and Shetland Sheepdogs; however, many other breeds can also be affected. The condition is associated with, and also aggravated by, ultraviolet light. It is suggested that UV damage exposes novel antigens that lead to autoimmune and cytotoxic reactions.
In the early stages of the disease, the nasal planum loses its cobblestone appearance. Depigmentation is a common feature (Figure 1). This is generally followed by crusting, scaling, erythema, erosions and ulcerations. Secondary infection is often present (Figure 2). Although in most cases the lesions are confined to the nose, the periocular areas and foot pads can also become involved.
The diagnosis is confirmed on histology, where hydropic degeneration and apoptosis of the basal keratinocytes is seen. In addition, an interface dermatitis, with a lymphoplasmacytic cell infiltrate and pigmentary incontinence, is also present. It is best practice to take the biopsies only after mucocutaneous pyoderma has been ruled out.
Topical tacrolimus ointment, or potent glucocorticoid ointment, is the first-line treatment for most cases. In cases with more extensive lesions, concurrent systemic treatment with ciclosporin, prednisolone or azathioprine can be given in the initial phase until remission, and then maintained on topical treatment. Sun avoidance is important in the long-term management.
Exfoliative cutaneous lupus erythematosus
ECLE is a chronic progressive condition, characterised by generalised scaling and crusting lesions. This condition has been mainly recognised in the GSP, where an autosomal recessive mode of inheritance has been identified. It has also recently been described in the Hungarian Vizsla (a breed which shares a common ancestry with the GSP).
Most affected dogs are presented any time from 10 weeks of age with scaling and alopecia which involves the muzzle (Figure 3), pinnae and dorsal aspects of the trunk. As the disease progresses, crusting, ulcerations and secondary infections are seen. Intermittent pyrexia, peripheral lymphadenopathy, intermittent lameness and reluctance to move are seen in some cases. The condition can affect the reproductive function.
This is supported by histopathological findings of an interface dermatitis which involves the epidermis and the hair follicle infundibulum. T-lymphocytes target the dermoepidermal interface. Destruction of the sebaceous glands in some cases can confuse the condition with sebaceous adenitis.
Overall this variant of lupus responds poorly to treatment and eventually most affected dogs are euthanised, because of poor quality of life. Various treatments to improve quality of life have been used with varying responses. They include a combination of tetracycline or doxycycline and nicotinamide, oral glucocorticoids, azathioprine, ciclosporin, leflunomide, mycophenolate mofetil and hydroxychloroquine.
Mucocutaneous lupus erythematosus
MCLE is an ulcerative condition and, as the name suggests, has a mucocutaneous distribution. It has been described mainly in adult German Shepherd Dogs and their crosses; however, other breeds can also be affected.
The main signs are symmetrical erosions and ulcerations affecting the mucosal sites of and around the genital (Figure 4) and anal areas. The periocular, perioral and perinasal sites can also be involved. If the anal and genital mucosae are involved, dogs exhibit signs of pain during defecation or urination. Crusting and hyperpigmentation are seen in areas where the ulcers have been present previously. Ulceration in the oral cavity has also been reported.
The diagnosis is supported by histopathological findings of a lymphocyte-rich interface dermatitis, with apoptosis and hydropic changes of basal keratinocytes.
Remission can be achieved with immunosuppressive doses of prednisolone and maintained using the lowest possible dose and frequency of the drug. Other immunosuppressive drugs such as azathioprine, ciclosporin and mycophenolate mofetil are alternatives to consider.
Vesicular cutaneous lupus erythematosus
VCLE is seen in Shetland Sheepdogs, Collies and their crosses which suggests there is a strong genetic predisposition. Affected dogs are mainly middle-aged or older. Most cases appear to have a summer onset suggesting that exposure to UV light may be a triggering factor.
It is a non-pruritic condition and in the early stages erythema and vesicles are seen; however, they rapidly slough leaving an erosive and ulcerative dermatitis. The distribution is mainly ventral involving axillae, abdomen, groin and medial aspects of the thighs. The lesions are often arranged in serpiginous or polycyclic configurations. Some dogs may show ulceration at mucocutaneous junctions and the oral cavity. Secondary bacterial infections are common.
In addition to the history and clinical signs, the diagnosis is supported by the presence of a lymphocyte-rich interface dermatitis with hydropic degeneration of basal keratinocytes and apoptosis that is seen as intrabasal clefts and vesiculation.
Responses to immunosuppressive doses of prednisolone (2mg/kg q24h), ciclosporin (5mg/kg q24h) and azathioprine (2mg/kg q24h) have been reported. The merit of each drug has to be assessed on a case-by-case basis. Avoidance of sunlight is important in the management of the disease.
Cutaneous lupus erythematosus encompasses a group of autoimmune skin diseases, of which discoid lupus erythematosus is the most likely one to be encountered in general practice.
There are strong genetic and breed predispositions for the diseases. Diagnosis based on history and clinical examination should be confirmed by histological examination of affected tissues. They require long-term management with topical and/or systemic immunosuppressive drugs and so careful monitoring is recommended.