Skin nontumor
Infectious disorders
Virus associated trichodysplasia spinulosa


Topic Completed: 1 April 2011

Minor changes: 21 August 2020

Copyright: 2002-2020, PathologyOutlines.com, Inc.

PubMed Search: Virus associated trichodysplasia spinulosa

Mowafak Hamodat, M.B.Ch.B., M.Sc.
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Cite this page: Hamodat M. Virus associated trichodysplasia spinulosa. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/skinnontumorVATS.html. Accessed October 21st, 2020.
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
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