[510] Herpetic Dermatitis: Correlation of Clinical Impression, Histopathologic Findings and PCR

Christopher L Kinonen, Briana C Gleason, Antoinette B Thomas, Karen L Kaul, Geoffrey Turner, Thomas A Victor, Thomas L Cibull. Evanston Hospital - NorthShore University HealthSystem, Evanston, IL; Diagnostic Pathology Medical Group, Sacramento, CA

Background: Herpetic dermatitis (HD) due to herpes simplex virus (HSV) and varicella zoster virus (VZV) can present with similar clinical and histologic features, although treatment for these two entities differ. Confounding matters, viral cytopathic changes are not always observed in biopsy specimens. Therefore, PCR can play an integral role in the definitive diagnosis of HD, and in the distinction of VZV from HSV-1/2. We correlated clinical impression, histologic findings and PCR results. We also describe cases of HD without viral change (“herpes incognito”) that histologically demonstrate the pattern of a dermal hypersensitivity reaction (DHR).
Design: 40 patients with skin biopsies from NorthShore University HealthSystem (2004-2011) had PCR performed to detect HSV-1/2 or VZV. Patient demographics, clinical impression and histologic characteristics were reviewed and correlated with PCR findings.
Results: Patient demographics and results are illustrated in tables 1 and 2. Sites include head & neck, face, chest, abdomen, back, extremities, penis, and perineum.

Patient Demographics

Total Number of Patients	Mean Age	Female	Male
40	53 (range 10-90)	22 (55%)	18 (45%)

Results

Clinical Impression	Histologic Viral Changes	PCR Positive	HSV-1	HSV-2	VZV	HSV&VZV
Herpetic dermatitis (28)	Present (21/28)	21/21	8	2	11	0
	Absent (7/28)	3/7	1	1	1	0
Other (12)	Present (12/12)	12/12	7	1	2	2

Overall, there was discordance between the clinical impression and histologic findings in 19 cases (48%) and PCR confirmed HSV or VZV infection in 15 of these 19 cases. In PCR confirmed cases of herpes where the clinical impression was HD but histologic viral changes were absent, histopathologic findings demonstrated a superficial and deep perivascular mixed cell dermatitis with eosinophils (DHR).
Conclusions: 1.Studies have reported HD (mostly commonly secondary to VZV) without diagnostic viral cytopathic effect as “herpes incognito”. These cases usually demonstrate a superficial and deep perivascular and perifollicular lymphocytic infiltrate without significant eosinophils. We observed similar findings in 3 cases (2HSV, 1 VZV) but unique to this study, our cases contained a prominent eosinophilic infiltrate, mimicking a DHR.
2.The results of this study suggest that routine use of PCR for definitive diagnosis of HD should be considered when there is a clinical suspicion of herpes virus infection, even when there is a lack of specific histopathologic findings.
3.DHR should be recognized as one histologic manifestation of herpes incognito.
Category: Dermatopathology

Monday, March 19, 2012 11:30 AM

Platform Session: Section F, Monday Morning