Porphyria cutanea tarda

To the Editor:

In the journal's Photo Rounds, Drs Sauret, Yale, and Ahiarah present a case of vesiculobullous disease ("Rupturing bullae not responding to antibiotics," J Fam Pract 2004; 53112]:981-983). We would like to offer additional comment we believe pertinent to family physicians.

In obtaining a biopsy in patients with vesiculobullous eruptions, there are several important factors to be considered compared with most other dermatoses. (1) First, biopsy specimens for immunofluorescence examinations cannot be submitted in the usual specimen preservatives. Instead, they need to be submitted in special transport media for immunofluorescence (typically Michel's medium) or as "fresh" specimens. For the latter, the physician uses a sterile container lined with saline-moistened gauze, into which the biopsy specimen is sealed and then transported to the pathologist "stat" or frozen until picked up. Perilesional skin is best for direct immunofluorescence testing of bullous diseases. Second, an additional specimen should be sent for routine histology. This can be accomplished either by doing two biopsies or by sectioning 1 sufficiently large specimen. Third, lesional skin is required for pathologic evaluation. However, with vesiculobullous eruptions, including perilesional skin allows a point of adherence for the roof of the lesion to the remainder of the lesion. The fourth difference is that a sample of the patient's serum is required for indirect immunofluorescence. Last, because of these logistics, it may be helpful to communicate with the dermatopathologist when biopsying lesions where immunofluorescence studies are considered. Although similar to lesion sampling in other dermopathies, but of critical importance in vesiculobullous disease, choice of lesions for sampling is important. The ideal lesions are fresh (less than 24-48 hours old), intact, and nonexcoriated vesiculobullae, with normal or erythematous perilesional skin for inclusion in the biopsy field.

In teaching residents about vesiculobullous disease, our simplified approach is to state that all primary care physicians should be facile with 3 categories. The first is infections--both viral, such as herpes simplex, varicella-zoster, and Enteroviral (including Coxsackie) infections--and bacterial, including bullous impetigo and staphylococcal scalded skin syndrome. The second category is acute eczematous tissue reactions including allergic contact dermatitis. The third is exogenous trauma, such as thermal burns, bug bites, and friction-induced lesions. The fourth category includes the less common inflammatory bullous diseases and may be within the purview of interested primary care physicians but is always fair game for referral--sometimes urgently. A partial list includes pemphigus, bullous pemphigoid, porphyria cutanea tarda, epidermolysis bullosa, erythema multiforme, drug eruptions, dermatitis herpetiformis and toxic epidermal necrolysis. Division into these categories may be helpful in delineating further workup, including culture and biopsy for pathology and immunofluorescence.

REFERENCE

(1.) Vesicular and bullous diseases (Chapter 16). In: Habif TP. Clinical Dermatology: A Color Guide to Diagnosis and Therapy. 4th ed. New York, NY: Mosby, Inc; 2004:547-554.

FAST TRACK Primary care physicians should be facile with 3 categories when diagnosing vesiculobullous disease

Gary N. Fox, MD Medical College of Ohio; Mercy Health Partners Family Practice Residency, Toledo

Gregory L. Swartz, DO Ohio University; Mercy Health Partners Family Practice Residency, Toledo

Darius R. Mehregan Wayne State University, Detroit MI, and Clinical Associate Professor of Pathology, Medical College of Ohio, Toledo

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