Trichodysplasia spinulosa (also known by many other names, including viral-associated trichodysplasia spinulosa, viral-associated trichodysplasia, pilomatrix dysplasia and ciclosporin-induced folliculodystrophy, although the last is a misnomer) is a
organ transplant recipients, on regimens of immunosuppressive drugs.[2][3] As of early 2016, a total of 32 cases had been reported in the medical literature.[2] Despite its rarity, TS is believed to be underdiagnosed, and the growing population of patients on immunosuppressive drug regimens suggests its incidence may rise.[2][3] TS has been described as an emerging infectious disease.[4]
Symptoms and signs
The disease is characterized by flesh-colored to
Pruritus (itching) has been described in about a third of reported cases.[2] Facial papules are generally 1- to 3-mm in size.[5]: 415 The condition is considered to be benign, but can be disfiguring; the spines are often prominent, and in later stages the affected facial skin thickens noticeably.[2][3]
Causes
TS has been reported almost exclusively in immunocompromised patients, primarily
There is compelling evidence that trichodysplasia spinulosa is caused by a
antibodies against viral proteins) in immunocompetent adults range from 70 to 80% in different sample populations.[3][7][8] TSPyV infects the skin, but viral DNA is rarely detectable there in asymptomatic individuals even if they possess antibodies to the virus indicating exposure.[3] It is not known whether TS represents new primary infection or opportunistic reactivation of a latent infection.[3]
Mechanism
The hyperproliferation of keratinocyteinner root sheath cells in which large aggregates of viral particles can be found suggests that TSPyV actively replicates in these cells. This is thought to underlie the clinical manifestations of TS. However, the precise mechanism is not well characterized.[3] There is limited evidence implicating the large tumor antigen as responsible for inducing cellular proliferation through pathways involving phosphorylated retinoblastoma protein (pRB).[9]
Diagnosis
acanthosis) in TS (A2, B2); high-power representative examples of hair follicles showing enlarged and dysmorphic appearance in TS (A3, B3). Inset in B3 shows characteristic eosinophilic protein granules, probably trichohyalin (arrowheads). H&E stain. Scale bars are 100μm.[9]
TS can be diagnosed based on clinical observations, but is usually confirmed by
quantitative PCR, as affected skin demonstrates much higher viral loads compared to unaffected skin or to asymptomatic individuals who test positive for viral DNA.[2][3]
Differential diagnosis includes other visually similar conditions affecting the hair follicles, many of which appear as drug side effects.[2] A proposed classification system lists TS as one of a group of cutaneous conditions with similar manifestations and distinct etiologies, collectively called the digitate keratoses.[10] Although confirmed TS is rare, the condition is thought to be underdiagnosed.[2]
Treatment
There have been too few cases of TS reported for a standard treatment to be established. In some cases, improvement in immune function has been noted to produce spontaneous improvement in TS symptoms. This pattern is consistent with the behavior of other viral diseases found in immunocompromised patients, most relevantly with the
oncogenic. The natural history of untreated TS is not known and no long-term studies of its progress have been performed. Improvement in immune function has been reported to resolve symptoms in some individual cases. Treatment with antiviral drugs has also been reported to improve symptoms, but only as long as treatment continues.[2][3]
History
TS was first described in a 1995
rolling circle amplification to recover viral DNA from TS lesions and thus discovered a novel polyomavirus, trichodysplasia spinulosa polyomavirus (TSPyV). There is compelling evidence that TSPyV is the direct causative agent of TS.[2][3]
