Tests
1st tests to order
dermoscopy
Test
Confirmatory test of the disease; to differentiate from guttate psoriasis[18]
Result
orange-yellowish structureless areas, focal dotted vessels, and nondotted vessels
skin biopsy
Test
Histopathologic exam confirms the disease.[4]
Specimens may also be analyzed for clonality with next-generation sequencing of T-cell receptor beta and gamma genes.[20][21]
Routine performance of T-cell receptor gene rearrangement is not required when there is clinical and histologic concordance for a diagnosis of pityriasis lichenoides et varioliformis acuta or lymphomatoid papulosis.[21][22]
Result
pityriasis lichenoides et varioliformis acuta: wedge-shaped, dense, and diffuse dermal CD8+ predominant lymphocytic infiltrate. Epidermal apoptotic and necrotic keratinocytes, neutrophilic inclusions, spongiosis, and focal parakeratosis. Next-generation sequencing may be positive for T-cell clonality. Pityriasis lichenoides chronica: superficial CD4+ T-dominant lymphocytic, band-like, sparsely perivascular infiltrate. Slight parakeratotic scale, minimal keratocytic necrosis, and spongiosis in the epidermis. Febrile ulceronecrotic Mucha-Habermann disease: prominent lymphocytic and neutrophilic infiltrate, pronounced epidermal necrosis and ulceration, and leukocytoclastic vasculitis
Tests to consider
antistreptolysin titers
Test
Consider checking if clinically suspecting infectious origin or severe ulceronecrotic form of disease.[4]
Result
to exclude streptococci
Epstein-Barr virus IgM/IgG viral capsid antigen and nuclear antigen antibody
Test
Consider checking if clinically suspecting infectious origin or severe ulceronecrotic form of disease.[4]
Result
to exclude Epstein-Barr virus
monospot or heterophil antibody test
Test
Consider checking if clinically suspecting infectious origin or severe ulceronecrotic form of disease.[4]
Result
to exclude Epstein-Barr virus
hepatitis B surface antigen, antisurface antibody, and anticore IgM
Test
Consider checking if clinically suspecting infectious origin or severe ulceronecrotic form of disease.[4]
Result
to exclude hepatitis B
hepatitis C virus antibody
Test
Consider checking if clinically suspecting infectious origin or severe ulceronecrotic form of disease.[4]
Result
to exclude hepatitis C
HIV screening
Test
Consider checking if clinically suspecting infectious origin or severe ulceronecrotic form of disease.[4]
Result
to exclude HIV
rapid plasma reagin
Test
Consider checking if clinically suspecting infectious origin or severe ulceronecrotic form of disease.[4]
Result
to exclude syphilis
throat cultures
Test
Consider checking if clinically suspecting infectious origin or severe ulceronecrotic form of disease.[4]
Result
to exclude bacterial etiology
toxoplasma Sabin-Feldman dye test, indirect immunofluorescence/hemagglutination
Test
Consider checking if clinically suspecting infectious origin or severe ulceronecrotic form of disease.[4]
Result
to exclude toxoplasmosis
erythrocyte sedimentation rate
Test
Consider checking if clinically suspecting infectious origin or severe ulceronecrotic form of disease.[4]
Result
elevated in febrile ulceronecrotic Mucha-Habermann disease
CRP
Test
Consider checking if clinically suspecting infectious origin or severe ulceronecrotic form of disease.[4]
Result
elevated in febrile ulceronecrotic Mucha-Habermann disease
serum LDH
Test
Consider checking if clinically suspecting infectious origin or severe ulceronecrotic form of disease.[4]
Result
elevated in febrile ulceronecrotic Mucha-Habermann disease
WBC count
Test
Consider checking if clinically suspecting infectious origin or severe ulceronecrotic form of disease.[4]
Result
leukocytosis in febrile ulceronecrotic Mucha-Habermann disease
serum albumin
Test
Consider checking if clinically suspecting infectious origin or severe ulceronecrotic form of disease.[4]
Result
hypoalbuminemia in febrile ulceronecrotic Mucha-Habermann disease
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