The Dermatologist’s Board Review - March 2017

The contents of these questions are taken from the Galderma Pre-Board Webinar. The Pre-Board Webinar is now an online course. For details, go to www.pre-board.com.

1. The diagnosis is:

a) Familial benign pemphigus (Hailey-Hailey disease)
b) Paraneoplastic pemphigus
c) Pemphigus vulgaris
d) Pemphigus foliaceus
e) Epidermolysis bullosa simplex

2. This 8-year-old child had a 6-month history of these facial lesions. Mucous membranes were uninvolved. Potassium hydroxide (KOH) preparation and fungal and bacterial cultures were negative. Repeated courses of cephalexin and dicloxacillin failed to affect this rash. The most likely diagnosis is:

a) Juvenile pemphigus vulgaris
b) Neonatal lupus erythematosus
c) Antibiotic-resistant bullous impetigo
d) Juvenile pemphigus foliaceus
e) Tinea faciei

3. Antibasement membrane zone antibodies in this disease:

a) Belong to the IgA class
b) Can usually be detected by indirect IgG immunofluorescence
c) Can usually be detected by indirect complement (C3) binding immunofluorescence
d) Bind the 230-Kd bullous pemphigoid antigen
e) Do not cross the placenta

1. The diagnosis is:

c) Pemphigus vulgaris

This Figure shows suprabasal epithelial separation (“tombstoning”) and microvesicle formation. Acantholysis is not readily apparent but basal cells are poorly adherent to each other. These changes are diagnostic for pemphigus vulgaris and appear to be directly related to pemphigus autoantibody binding to extracellular domains of desmoglein 3.

Reference
Lever WF, Schaumburg-Lever G. Histopathology of the Skin. 7th ed. Philadelphia, PA: Lippincott Williams and Wilkins; 1990:116.

2. This 8-year-old child had a 6-month history of these facial lesions. Mucous membranes were uninvolved. Potassium hydroxide (KOH) preparation and fungal and bacterial cultures were negative. Repeated courses of cephalexin and dicloxacillin failed to affect this rash. The most likely diagnosis is:

d) Juvenile pemphigus foliaceus

In this 8-year-old child, the diagnosis of juvenile pemphigus foliaceus was proven by direct immunofluorescence and routine histology. Although any of the other diagnoses noted in the question is possible, based on clinical morphology, KOH scraping, and fungal culture excluded tinea faciei and bacterial cultures would have confirmed the presence of a treatable bacterial pathogen. The cutaneous lesions of neonatal lupus erythematosus would have occurred on or shortly after birth and disappeared within the first year of life. Pemphigus vulgaris would have morphologically appeared more erosive or bullous, rather than papulosquamous (ie, seborrheic-like).

References
Walker DC, Kolar KA, Hebert AA, Jordan RE. Neonatal pemphigus foliaceus. Arch Dermatol. 1995;131(11):1308-1311.
Rico MJ. Autoimmune blistering diseases in children. Semin Dermatol. 1995;14(1):54-59.
Nishikawa T, Hashimoto T, Shimizu H, Ebihara T, Amagai M. Pemphigus: from immunofluorescence to molecular biology. J Dermatol Sci. 1996;12(1):1-9.
Stanley JR. Pathophysiology and therapy of pemphigus in the 21st century. J Dermatol. 2001;28(11):645-646.

3. Antibasement membrane zone antibodies in this disease:

c) Can usually be detected by indirect complement (C3) binding immunofluorescence

This pregnant woman has herpes gestationis (pemphigoid gestationis). Herpes gestationis can be readily distinguished from pruritic urticarial papules and plaques of pregnancy (PUPPP) clinically by its earlier onset during pregnancy, its tendency to begin within or around the umbilicus, the presence of targetoid lesions (mimicking erythema multiforme), the relative frequency of blisters compared with urticarial plaques, and its tendency to spare the striae distensiae (in contrast to PUPPP).

Neonates of affected women may be at risk of premature birth. Herpes gestationis patients commonly are positive for HLA-B8 and HLA-DR3/DR4. Herpes gestationis is characterized by complement-fixing IgG class autoantibodies to the NC16A domain of type XVII collagen. As a result, direct immunofluorescence reveals linear staining along the dermoepidermal junction. Whereas only about 25% of all herpes gestationis patients have detectable autoantibodies in their sera by routine indirect immunofluorescence, virtually 100% will be detectable if a modified complement-fixation indirect immunofluorescence test (“herpes gestationis assay”) is employed. These autoantibodies, however, are present in very low titer and can be easily missed if higher dilutions are used instead in the assay.

References
Wakelin SH, Black MM. The autoimmune bullous diseases. J R Coll Physicians Lond. 1997;31(4):364-368.
Shornick JK. Dermatoses of pregnancy. Sem Cutan Med Surg. 1998;17(3):172-181.
Jenkins RE, Hern S, Black MM. Clinical features and management of 87 patients with pemphigoid gestationis. Clin Exp Dermatol. 1999;24(4):255-259.
Engineer L, Bhol K, Ahmed AR. Pemphigoid gestationis: a review. Am J Obstet Gynecol. 2000;183(2):483-491.

Jo-David Fine, MD, MPH, FRCP, is board certified in internal medicine, dermatology, and diagnostic and laboratory immunodermatology. Dr Fine is currently professor of medicine (dermatology) and pediatrics at Vanderbilt University School of Medicine in Nashville, TN.

Ron J. Feldman, MD, PhD, is assistant professor in the department of dermatology at Emory University School of Medicine in Atlanta, GA.