Tzanck test

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Tzanck test
Tzanck test.png
A positive Tzanck test, showing three multinucleated giant cells ("Tzanck cells") in center.
Purposediagnosis of varicella-zoster virus and herpes

In dermatopathology, the Tzanck test, also Tzanck smear, is scraping of an ulcer base to look for Tzanck cells. It is sometimes also called the chickenpox skin test and the herpes skin test. It is a simple, low-cost, and rapid office based test. [1]

Contents

Tzanck cells (acantholytic cells) are found in:

Arnault Tzanck did the first cytological examinations in order to diagnose skin diseases. [3] To diagnose pemphigus, he identified acantholytic cells, and to diagnose of herpetic infections he identified multinucleated giant cells and acantholytic cells. He extended his cytologic findings to certain skin tumors as well.

Even though cytological examination can provide rapid and reliable diagnosis for many skin diseases, its use is limited to a few diseases. In endemic regions, Tzanck test is used to diagnose leishmaniasis and leprosy. For other regions, Tzanck test is mainly used to diagnose pemphigus and herpetic infections. Some clinics use biopsies even for herpetic infections. [4] This is because the advantages of this test are not well known, and the main textbooks of dermatopathology do not include dedicated sections for cytology or Tzanck smear. [5] A deep learning model called TzanckNet has been developed to lower the experience barrier needed to use this test. [6]

Procedure

  1. Unroof vesicle and scrape base w/ sterile №15 scalpel blade
  2. Smear with cotton stick onto a clean glass slide
  3. Fix w/ gentle heat or air dry
  4. Fix w/ MeOH (Methanol)
  5. Stain w/ Giemsa, methylene blue or Wright’s stain.
  6. Microscopic examination using an oil immersion lens. (Look for multinucleated giant cells) [7]

A modified test can be performed using proprietary agents which requires fewer steps and allows the sample to be fixed quicker.

Cytologic findings

For microscopic evaluation, samples are first scanned with low magnification objectives (X4 and X10) and then examined in detail with the high magnification objective (X100). The X4 objectives are used to select the areas to investigate in detail and to detect some ectoparasites, but the basis of the cytological diagnostic process is the X10 objective. With X10 magnification, the individual characteristics of the cells, the relationship of the cells to each other and the presence of some infection and infestation agents are evaluated. For this reason, most of the cytological examination is spent at this magnification, and most samples are diagnosed at this magnification. The key cytological findings that are observed at low magnification or, in other words, should be investigated according to the clinical characteristics of the patient are as follows: acantholytic cells, tadpole cells, granulomatous inflammation, infectious agents and increases in specific cells.

Major indications, cytologic findings and diagnostic value of Tzanck smear test [8]

DiseasesCytologic findingsDiagnostic value
I. Cutaneous infections
Bacterial infections
Bullous impetigo Dyskeratotic acantholytic cells, abundant neutrophils and clusters of cocci92% sensitive and 100% specific
Staphylococcal scalded skin syndrome (SSSS)Dyskeratotic acantholytic cells, absence of abundant neutrophils and cocciA Tzanck smear may be a rapid test to distinguish toxic epidermal necrolysis from SSSS
Mycobacterial infectionsNegative images of mycobacteriae, acid-fast bacilliMaximum acid-fast bacilli positivity (94%) in cases showing caseation necrosis with or without granulomas
Bacillary angiomatosis Clumps of coccobacilli of B Henselae in Warthin-Starry-stained smears
Fungal infections
Dermatophytic infectionsHyphae and spores
Candidiasis Pseudohyphae and sporesPseudohyphae and spores in 90% of patients with candida folliculitis
Aspergillosis Septate hyphae with 45-degree angle branching and/or aspergillus heads
Blastomycosis Broad-based budding spores57.7 - 93% sensitive
Sporotrichosis Spherical, oval or cigar-shaped yeasts and asteroid bodies84.9% sensitive and 57.9% specific
Viral infections
Herpetic infections Acantholytic cells, multinucleated giant cells and eosinophilic inclusion bodies53.1 - 86% sensitive and 100% specific
Hand, foot and mouth disease Syncytial nuclei, absence of acantholytic cells172% sensitive and 100% specific
Human papillomavirus infections Koilocytes75% sensitive and 100% specific
Molluscum contagiosum Intracytoplasmic inclusion bodies (“Henderson-Patterson’s bodies”)
Milker’s nodule and orfIntracytoplasmic inclusion bodies (“Guarnieri’s bodies”)
Parasitic infections
Leishmaniasis Ellipsoid-shaped Leishman-Donovan bodie30 - 82.6% sensitive and 100% specific
DemodicosisMore than 5 Demodex mites/cm2The diagnostic value of cytology for diagnosing Demodex folliculitis is higher than that of histopathology. The sensitivity of histopathology is 60%, whereas that of cytology is 93.3%
Cutaneous amoebiasis Trophozoites of Entamoeba histolyticaDirect specimens or PAS and acid phosphatase-stained specimens in cases with doubtful direct specimens show trophozoites of Entamoeba histolytica
II. Immunobullous disorders
Pemphigus Acantholytic cells with direct immunofluorescence positivityWith the use of direct immunofluorescence examination, the specificity of cytology for diagnosing pemphigus can be increased from 43% to 100%.
Erythema multiforme, Toxic epidermal necrolysisApoptotic and necrotic cells, absence of acantholytic cellsA Tzanck smear may be a rapid test to distinguish toxic epidermal necrolysis from SSSS
III. Genodermatoses
Hailey-Hailey disease Acantholytic cells without direct immunofluorescence positivityDirect immunofluorescence examination should be made for differentiation from pemphigus.
Darier’s disease Acantholytic cells, corps ronds, grains
IV. Spongiotic dermatitisPresence of more than 10 tadpole cells at x100 magnification
Contact dermatitis Tadpole cells and lymphocytes83% sensitive and 100% specific
V. Granulomatous diseasesGranuloma formation and multinucleated giant cellsThe main purpose of cytological examination in granulomatous dermatitis is to detect infectious agents. Foreign body materials are very specific for foreign body granuloma.
Granuloma annulare Palisading granuloma and mucin
Necrobiosis lipoidica Palisading granuloma and necrobiotic materials
Foreign-body granuloma Foreign body
Juvenile xanthogranuloma Touton type giant cells and foamy cells
VI. Tumoral lesions
Benign tumoral lesions
Mastocytoma Abundant mast cellsTzanck smear test is useful for rapid diagnosis of mastocytoma in children
Sebaceous hyperplasia Clusters of sebocytes
Seborrheic keratosis Hyperkeratosis and horny cysts87.5% sensitive and 80.8% specific
Melanocytic nevi Dermal and epidermal type nevoid cells87.5% sensitive and 100% specific
Eruptive vellus hair cysts Abundant vellus hairs
Malignant tumoral lesionsCellular atypia including mitosis, poikilokaryosis, poikilocytosis, nuclear contour irregularity, prominent nucleoli and nuclear molding
Basal cell carcinoma Clusters of basaloid cellsThe most common reason to use cytological examination in malignant tumoral diseases is to distinguish basal cell carcinoma from other tumors, such as squamous cell carcinoma and melanoma. Tzanck smear test is 97% sensitivity and 86% specificity for the diagnosis of basal cell carcinoma.
Squamous cell carcinoma Cytologic atypia of keratinocytes
Melanoma Atypical melanocytes
Lymphoma Atypical lymphocytes
Paget’s disease Isolated or clusters of Paget’s cells
Kaposi’s sarcoma Cigar-shaped spindle cells

Tzanck smear examples

References

  1. Durdu M (2019). Cutaneous Cytology and Tzanck Smear Test. Springer International Publishing. ISBN   978-3-030-10721-5.
  2. Folkers E, Oranje AP, Duivenvoorden JN, van der Veen JP, Rijlaarsdam JU, Emsbroek JA (August 1988). "Tzanck smear in diagnosing genital herpes". Genitourinary Medicine. 64 (4): 249–54. doi:10.1136/sti.64.4.249. PMC   1194227 . PMID   3169755.
  3. Tzanck A (1947). "Le cyto-diagnostic immédiat en dermatologie". Presse Médicale.
  4. Horn TD (December 2008). "Commentary: heading the wrong way: the disappearing Tzanck smear". Journal of the American Academy of Dermatology. 59 (6): 965–966. doi:10.1016/j.jaad.2008.08.025. ISSN   1097-6787. PMID   18929430.
  5. Kelly B, Shimoni T (2009-06-01). "Reintroducing the Tzanck Smear" . American Journal of Clinical Dermatology. 10 (3): 141–152. doi:10.2165/00128071-200910030-00001. ISSN   1179-1888. PMID   19354329. S2CID   23928319.
  6. Noyan MA, Durdu M, Eskiocak AH (2020-10-27). "TzanckNet: A convolutional neural network to identify cells in the cytology of erosive-vesiculobullous diseases". Scientific Reports. 10 (1): 18314. doi:10.1038/s41598-020-75546-z. PMC   7591506 . PMID   33110197.
  7. Pettit, Normal Microbiota of the Skin, ATSU School of Osteopathic Medicine Arizona, Lecture Slides. Jan 2013.
  8. Durdu M, Seckin D, Baba M (January–February 2011). "The Tzanck Smear Test: Rediscovery of a Practical Diagnostic Tool". Skinmed. 9 (1): 23–32. PMID   21409959 . Retrieved 18 September 2023.