Diseases |
Cytologic findings |
Diagnostic value |
I. Cutaneous infections |
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Bacterial infections |
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Bullous impetigo |
Dyskeratotic acantholytic cells, abundant neutrophils and clusters of cocci |
92% sensitive and 100% specific |
Staphylococcal scalded skin syndrome (SSSS) |
Dyskeratotic acantholytic cells, absence of abundant neutrophils and cocci |
A Tzanck smear may be a rapid test to distinguish toxic epidermal necrolysis from SSSS |
Mycobacterial infections |
Negative images of mycobacteriae, acid-fast bacilli |
Maximum 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 |
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Fungal infections |
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Dermatophytic infections |
Hyphae and spores |
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Candidiasis |
Pseudohyphae and spores |
Pseudohyphae and spores in 90% of patients with candida folliculitis |
Aspergillosis |
Septate hyphae with 45-degree angle branching and/or aspergillus heads |
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Blastomycosis |
Broad-based budding spores |
57.7 - 93% sensitive |
Sporotrichosis |
Spherical, oval or cigar-shaped yeasts and asteroid bodies |
84.9% sensitive and 57.9% specific |
Viral infections |
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Herpetic infections |
Acantholytic cells, multinucleated giant cells and eosinophilic inclusion bodies |
53.1 - 86% sensitive and 100% specific |
Hand, foot and mouth disease |
Syncytial nuclei, absence of acantholytic cells1 |
72% sensitive and 100% specific |
Human papillomavirus infections |
Koilocytes |
75% sensitive and 100% specific |
Molluscum contagiosum |
Intracytoplasmic inclusion bodies (“Henderson-Patterson’s bodies”) |
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Milker’s nodule and orf |
Intracytoplasmic inclusion bodies (“Guarnieri’s bodies”) |
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Parasitic infections |
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Leishmaniasis |
Ellipsoid-shaped Leishman-Donovan bodie |
30 - 82.6% sensitive and 100% specific |
Demodicosis |
More than 5 Demodex mites/cm2 |
The 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 histolytica |
Direct specimens or PAS and acid phosphatase-stained specimens in cases with doubtful direct specimens show trophozoites of Entamoeba histolytica |
II. Immunobullous disorders |
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Pemphigus |
Acantholytic cells with direct immunofluorescence positivity |
With the use of direct immunofluorescence examination, the specificity of cytology for diagnosing pemphigus can be increased from 43% to 100%. |
Erythema multiforme, Toxic epidermal necrolysis |
Apoptotic and necrotic cells, absence of acantholytic cells |
A Tzanck smear may be a rapid test to distinguish toxic epidermal necrolysis from SSSS |
III. Genodermatoses |
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Hailey-Hailey disease |
Acantholytic cells without direct immunofluorescence positivity |
Direct immunofluorescence examination should be made for differentiation from pemphigus. |
Darier’s disease |
Acantholytic cells, corps ronds, grains |
IV. Spongiotic dermatitis |
Presence of more than 10 tadpole cells at x100 magnification |
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Contact dermatitis |
Tadpole cells and lymphocytes |
83% sensitive and 100% specific |
V. Granulomatous diseases |
Granuloma formation and multinucleated giant cells |
The main purpose of cytological examination in granulomatous dermatitis is to detect infectious agents. Foreign body materials are very specific for foreign body granuloma. |
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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 |
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Benign tumoral lesions |
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Mastocytoma |
Abundant mast cells |
Tzanck smear test is useful for rapid diagnosis of mastocytoma in children |
Sebaceous hyperplasia |
Clusters of sebocytes |
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Seborrheic keratosis |
Hyperkeratosis and horny cysts |
87.5% sensitive and 80.8% specific |
Melanocytic nevi |
Dermal and epidermal type nevoid cells |
87.5% sensitive and 100% specific |
Eruptive vellus hair cysts |
Abundant vellus hairs |
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Malignant tumoral lesions |
Cellular atypia including mitosis, poikilokaryosis, poikilocytosis, nuclear contour irregularity, prominent nucleoli and nuclear molding |
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Basal cell carcinoma |
Clusters of basaloid cells |
The 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 |