Cutaneous lupus erythematosus

53 Cutaneous lupus erythematosus




INITIAL PRESENTATION


Ulceration, crusting and leucoderma on the nasal planum in a dog.



INTRODUCTION


Although discoid (cutaneous) lupus erythematosus is uncommon, it is still the most frequently encountered immune-mediated disease in general practice. Generally, the lesions are confined to the bridge of the nose and the nasal planum; however, they can occur on feet and other mucocutaneous sites, such as the genitalia and anal mucosa. The condition is aggravated by sunlight. There has been some discussion on the use of the term ‘discoid lupus erythematosus’, as the clinical presentation is different from that seen in humans and the histology of the condition is not lupus specific (it is also commonly seen in mucocutaneous pyoderma). It has been suggested that the term cutaneous lupus erythematosus may be more appropriate. This case report describes the condition on the nasal planum and the feet of a dog and is referred to as cutaneous lupus erythematosus.




CASE PRESENTING SIGNS


An 8-year-old, neutered male boxer was presented with a crusting and ulcerative dermatosis of the nose.



CASE HISTORY


Generally, lesions are first noted on the nose and less frequently other sites may become involved. An astute owner may also be aware of a seasonal exacerbation of the clinical signs. The duration of the condition varies between individuals, and it may wax and wane over several weeks or months. Pruritus is variable.


In this case the relevant history was:


• The dog was rehomed by a rescue centre, where it had been held for about 6 months.

• Lesions were present on the nose and the feet at the time the dog was first taken into the rescue centre, and had been investigated. A tentative diagnosis of discoid lupus erythematosus with secondary infection was made based on histopathological examination but a 6-week course of cefalexin had been prescribed to rule out the involvement of mucocutaneous pyoderma, which is indistinguishable from cutaneous lupus on histopathology.

• The condition only partially improved with the cefalexin, so the dog was prescribed 500 mg t.i.d. of oxytetracyline and 500 mg t.i.d.of nicotinamide for several months, again with a poor response.

• The present owner reported that the dog resented pedal examination and was only able to walk for short distances.

• The nasal lesions were prone to haemorrhage if traumatized.

• The dog was not pruritic.

• Appetite was unaffected.


CLINICAL EXAMINATION


Most frequently, lesions will be distributed on the bridge of the nose and the nasal planum. Erythema, ulceration, crusting, scaling and alopecia are the most common signs on the bridge of the nose. The nasal planum usually loses its cobblestone appearance, becoming smooth with depigmentation, crusting and ulceration. In rare cases, the condition may involve other sites, such as the ears, lip margins, periorbital areas, pinnae, genital areas and the feet.


The examination in this case revealed the following signs:


• Apart from a reactive peripheral lymphadenopathy, involving prescapular and popliteal lymph nodes, the general physical examination was unremarkable.

• Cutaneous lesions were limited to the nasal planum and the feet.

• The nasal planum had lost its cobblestone appearance, leaving a smooth surface with severe crusting, ulceration, hypopigmentation and a deep fissure on the nasal philtrum (Fig. 53.1).

• Painful lesions were present on the plantar aspects of all four feet consisting of well-demarcated ulceration with serpiginous borders at the junction of the central pads and the surrounding skin (Fig. 53.2).

• Crusting and hypopigmentation were evident on the footpads.

• The surrounding skin was markedly erythematous.

image

Figure 53.1 Crusting, ulceration and depigmentation on the nasal planum. Note the loss of the cobblestone appearance.


image

Figure 53.2 Plantar aspect of the foot, showing marked ulceration, crusting and erythema.




DIFFERENTIAL DIAGNOSES


The differential diagnoses included all the ulcerative conditions that affect the mucocutaneous sites:



• Cutaneous lupus erythematosus

• Pemphigus vulgaris

• Vasculitis

• Cutaneous lymphoma (epitheliotropic or non-epitheliotropic)

• Mucocutaneous pyoderma

• Drug eruption

• Erythema multiforme

• Metabolic epidermal necrosis

• Squamous cell carcinoma

• Deep mycoses

• Uveodermatological syndrome.


CASE WORK-UP


Given the previous history and histopathology results, cutaneous lupus erythematosus was still the most likely diagnosis despite the previous poor response to treatment. However, it is possible that a secondary infection was masking some other differential, or that the biopsy samples might have been obtained from inappropriate sites.


It was decided that a thorough work-up was required and the following tests were performed:


• Cytological examination of an impression smear from an ulcerated lesion, which revealed intra- and extracellular coccoid bacteria, but no acantholytic keratinocytes.

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Sep 3, 2016 | Posted by in SMALL ANIMAL | Comments Off on Cutaneous lupus erythematosus

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