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Skin-nontumor / Clinical Dermatology

Infectious disorders

Virus associated trichodysplasia spinulosa

Reviewer: Mowafak Hamodat MB.CH.B, MSc., FRCPC, Eastern Health, St. Johns (Canada) (see Reviewerspage)
Revised: 1 May 2011, last major update April 2011
Copyright: (c) 2002-2011, PathologyOutlines.com, Inc.


● Very rare (<10 cases reported) cutaneous eruption of spiny papules due to polyoma virus infection

Clinical description

● Usually affects face and ear, less often trunk and extremities; may cause alopecia
● Associated with kidney transplant, acute lymphocytic leukemia
● Similar to cyclosporine-induced follicular dystrophy and pilomatrix dysplasia

Microscopic description

● Abnormally maturing anagen hair follicles (no papillae, ectatic infundibula) with excessive inner root sheath differentiation, and hyperkeratotic infundibula (Am J Surg Pathol 2005;29:241)
● Hair follicles are dilated and contained hyperkeratotic and parakeratotic debris in place of hair shafts
● Hyperplastic areas of differentiation into hair matrix with cellular disorganization and loss of nuclear polarity

Electron microscopy

● Intranuclear polyoma-type virus particles

Differential diagnosis

Keratosis pilaris: usually arms and legs, small ecstatic infundibula with keratin plugs
Lichen spinulosis: children and adolescents, extensor arms, lateral thighs, neck and buttock, minute filiform horny spines grossly due to follicular infundibular hyperkeratosis
Drug induced folliculitis

End of Skin-nontumor / Clinical Dermatology > Infectious disorders > Virus associated trichodysplasia spinulosa

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