Chapter 6: Bullous Disorders

SUMMARY

• The antigenic expression in the basement membrane components of the skin is similar to that of the nail bed. This helps explain the involvement of the nail in bullous disease.

• Nail dystrophy is more common in pemphigus than pemphigoid disorders and commonly presents with paronychia, onychomadesis, and onycholysis.

• Nail dystrophy is a frequent component of many subtypes of epidermolysis bullosa, and clinical features can range from pachyonychia to erosion of the nail with subungual granulation tissue.

TIPS FOR DIAGNOSIS

• Blistering of the nails can occur before blistering of the skin in epidermolysis bullosa and nail dystrophy may be present in several family members in previous generations.

• A skin biopsy is the gold standard for diagnosing both chronic and inherited bullous diseases.

• Nail dystrophy in autoimmune bullous disorders often indicates increased disease severity.

TIPS FOR TREATMENT

• In many cases, treating the bullous disease will resolve nail symptoms in addition to skin symptoms.

• Autoimmune blistering disorders are treated systemically, often with corticosteroids and an adjuvant immunosuppressive like rituximab.

• Epidermolysis bullosa is managed through wound prevention and care, pain control, and nutrition supplementation.

DON’T FORGET

• Any patient, especially a pediatric patient, which presents with fragile skin that blisters in severity out of proportion to offending trauma should be considered for a possible diagnosis of epidermolysis bullosa.

• The nail presentation can vary widely among different types of bullous disease, so it is important to take nail pathology in conjunction with overall physical exam and history to develop a differential.

PITFALLS AND CAUTIONS

• Although nail findings are found often in epidermolysis bullosa, they are not necessarily pathognomonic for the disease. The entire patient presentation should be considered.

• Nail dystrophy relapse can occur just before the onset of a flair in autoimmune bullous diseases.

EXPERT PEARLS

• When acquiring a biopsy sample to evaluate for epidermolysis bullosa, the biopsy should come from a freshly induced blister. However, biopsy to diagnose pemphigus vulgaris should come from skin or mucosa that is intact.

• When differentiating paronychia caused by pemphigus vulgaris from other possible causes, know that in pemphigus vulgaris, histology will show suprabasal acantholysis that lacks spongiosis or exocytosis.

PATIENT EDUCATION POINTS

• Patients should be counseled on proper nail hygiene. For example, nails should be trimmed regularly straight across.

• Patients with epidermolysis bullosa need to be selective in material for clothing and shoes to avoid excessive mechanical trauma and prevent blistering.