Trichodysplasia spinulosa is a rare viral infection seen in immunocompromised patients. It is caused by reactivation of trichodysplasia spinulosa-associated polyomavirus (TSPyV). Patients develop flesh-colored or erythematous follicular papules on the central face, alopecia, and facial disfigurement. Primary exposure to TSPyV occurs in early childhood, and most people (63%-80% of immunocompromised and immunocompetent populations) become seropositive by adulthood. Infected individuals do not develop clinical manifestations unless in the setting of immunosuppression. Follicular inner root sheath keratinocyte hyperproliferation secondary to molecular interactions between host anti-oncogenes and viral antigens are thought to produce the characteristic spiny-filiform papular lesions.

Risk factors for development of trichodysplasia spinulosa reflect immunosuppression: AIDS, iatrogenic immunosuppression (use of immunosuppressive medication), solid organ transplant, and malignancy.

This condition was previously known as viral-associated trichodysplasia, cyclosporine-induced folliculodystrophy, pilomatrix dysplasia, and trichodysplasia of immunosuppression.