Skin inflammatory (nontumor)
Infectious disorders
Virus associated trichodysplasia spinulosa

Author: Mowafak Hamodat, M.D., MB.CH.B, MSc., FRCPC (see Authors page)

Revised: 19 October 2018, last major update April 2011

Copyright: (c) 2002-2018,, Inc.

PubMed Search: Virus associated trichodysplasia spinulosa

Cite this page: Hamodat, M. Virus associated trichodysplasia spinulosa. website. Accessed December 12th, 2018.
Definition / general
  • Very rare (< 10 cases reported) cutaneous eruption of spiny papules due to polyoma virus infection
Clinical features
  • 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 (histologic) 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 description
  • 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