Acessibilidade / Reportar erro

Herpes zoster incognito: an immunohistochemical diagnosis How to cite this article: Nazzaro G, Veraldi S. Herpes zoster incognito: an immunohistochemical diagnosis. An Bras Dermatol. 2020;95:401-2. ,☆☆ ☆☆ Study conducted at the Department of Pathophysiology and Transplantation, Università degli Studi di Milano, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy.

A 60-year-old woman presented with a 1 week history of an erythematosus and edematous plaque on her scalp. The lesion, 2.5 cm in diameter, was associated to mild pain (Fig. 1). Histopathological examination showed a massive inflammatory infiltrate in the dermis, especially surrounding sebaceous glands and responsible of oedema in the papillary dermis with initial dermo-epidermal vescicle formation (Fig. 2A). In the suspect of a herpetic infection, immunohistochemistry was performed, revealing negativity for Herpes Simplex virus (HSV) and positivity for Varicella Zoster virus (VZV) (Fig. 2B). Our diagnosis was therefore herpes zoster incognito.

Figure 1
Erythematous plaque with recent onset at the top of a 60 year-old woman.

Figure 2
A, Inflammatory infiltrate surrounding follicular epithelium and sebaceous gland. Initial bullous detachment at the dermo-epidermal junction (Hematoxylin & eosin, ×40). B, The primary involvement of the skin is on the sebaceous epithelium, as shown by immunohistochemistry specific for varicella zoster virus (Hematoxylin & eosin, ×40).

Herpes zoster (HZ), due to the reactivation of VZV, present in a latent state in sensory ganglia, can remain inactive for decades or also for the whole life. Essential condition is a previous contact, usually during infancy, with VZV. HZ is characterized by unilateral erythematosus-vesicular rash and a localized pain. Nevertheless, especially at the onset of an eruption or in forms considered as abortive, when lesions are macules, papules, and plaques, clinical diagnosis may be challenging. Microscopical examination can be used to confirm infection by herpesviruses, but sometimes typical signs such as multinucleated epithelial cells or ghosts of them are not encountered in a specimen. The term “herpes incognito” (from Latin, meaning not recognizable) has therefore been introduced.11 Böer A, Herder N, Blodorn-Schlicht N, Falk T. Herpes Incognito most commonly is herpes zoster and its histopathologic pattern is distinctive. Am J Dermatopathol. 2006;28:181-6.

The virus is transported from dorsal root or trigeminal ganglia via myelinated nerves which terminate at the isthmus of hair follicles. Consequently, the primary involvement of the skin is on follicular and sebaceous epithelium,22 Walsh N, Boutilier R, Glasgow D, Shaffelbug M. Exclusive involvement of folliculosebaceous units by herpes - a reflection of early herpes zoster. Am J Dermatopathol. 2005;27:189-94. as shown in the case presented. Spread of infection to the epidermis follows. This clue, that is pathognomonic of HZ and is not found in herpes simplex, can be easily confirmed by immunohistochemistry. This histological method, that can be used to distinguish the viral aetiology in tricky causes,33 Veraldi S, Fanoni D, Nazzaro G. Herpes zoster of the penis: an immunohistochemistry diagnosis. J Cutan Pathol. 2012;39:811-2. demonstrates that HSV affects primarily the epidermis and the upper portions of follicles only occasionally but never sebaceous epithelium or nerves. In fact, VZV spreads preferentially from dermal nerves to folliculosebaceous units and thence to the epidermis. Nevertheless, the reason why recurrent HSV infection primarily targets the epidermis, in contrast to HZV, which is preferentially directed to folliculosebaceous units, is not fully understood.

In a study involving 75 patients with a clinical differential diagnosis of herpetic infections,44 Böer A, Herder N, Blödorn-Schlicht N, Steinkraus V, Falk TM. Refining criteria for diagnosis of cutaneous infections caused by herpes viruses through correlation of morphology with molecular pathology. Indian J Dermatol Venereol Leprol. 2006;72:270-5. HZ was misdiagnosed as HSV infection in 30% of the cases as the clinicians were in difficult when vesicles were absent. From a histological point of view, herpetic folliculitis was detected in 28% of HZ, while it was not encountered in herpes simplex infections.

In conclusion, HZ may present with clinical variants, such as purpuric or hemorrhagic55 Veraldi S, Vaira F, Nazzaro G. Purpuric herpes zoster in patients in therapy with clopidogrel. J Clin Virol. 2015;69:122-4. in patients in antiplatelet or anticoagulant therapy and, gangrenous, bullous or disseminated HZ in immunocompromised patients. We described a case of herpes incognito, an underreported clinical variant of HZ, representing its abortive form, with distinctive clinical and histological features.

  • Financial support
    None declared.
  • How to cite this article: Nazzaro G, Veraldi S. Herpes zoster incognito: an immunohistochemical diagnosis. An Bras Dermatol. 2020;95:401-2.
  • ☆☆
    Study conducted at the Department of Pathophysiology and Transplantation, Università degli Studi di Milano, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy.

References

  • 1
    Böer A, Herder N, Blodorn-Schlicht N, Falk T. Herpes Incognito most commonly is herpes zoster and its histopathologic pattern is distinctive. Am J Dermatopathol. 2006;28:181-6.
  • 2
    Walsh N, Boutilier R, Glasgow D, Shaffelbug M. Exclusive involvement of folliculosebaceous units by herpes - a reflection of early herpes zoster. Am J Dermatopathol. 2005;27:189-94.
  • 3
    Veraldi S, Fanoni D, Nazzaro G. Herpes zoster of the penis: an immunohistochemistry diagnosis. J Cutan Pathol. 2012;39:811-2.
  • 4
    Böer A, Herder N, Blödorn-Schlicht N, Steinkraus V, Falk TM. Refining criteria for diagnosis of cutaneous infections caused by herpes viruses through correlation of morphology with molecular pathology. Indian J Dermatol Venereol Leprol. 2006;72:270-5.
  • 5
    Veraldi S, Vaira F, Nazzaro G. Purpuric herpes zoster in patients in therapy with clopidogrel. J Clin Virol. 2015;69:122-4.

Publication Dates

  • Publication in this collection
    24 July 2020
  • Date of issue
    May-Jun 2020

History

  • Received
    11 Mar 2019
  • Accepted
    23 July 2019
  • Published
    19 Mar 2020
Sociedade Brasileira de Dermatologia Av. Rio Branco, 39 18. and., 20090-003 Rio de Janeiro RJ, Tel./Fax: +55 21 2253-6747 - Rio de Janeiro - RJ - Brazil
E-mail: revista@sbd.org.br