Overview of histological findings in<unk> . Top row (A1-A3) shows healthy control; bottom row (B1-B3) shows TS skin. Low-magnification-power overview (A1, B1); high-power representative examples of epidermis showing thickening of the skin (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. TS can be diagnosed based on clinical observations, but is usually confirmed by histopathology of a lesional biopsy or a plucked spicule. Characteristic histological findings include enlarged and abnormally organized hair follicles and hyperproliferation of inner root sheath cells containing large eosinophilic trichohyalin granules. Antibodies against major capsid protein VP1, the major component of the viral capsid, can be used to confirm the presence of viral particles in cell nuclei. Electron microscopy can also be used to detect viral particles. Quantification of viral load can be performed using quantitative PCR, as affected skin demonstrates much higher viral loads compared to unaffected skin or to asymptomatic individuals who test positive for viral DNA. Differential diagnosis includes other visually similar conditions affecting the hair follicles, many of which appear as drug side effects. 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. Although confirmed TS is rare, the condition is thought to be underdiagnosed.
Trichodysplasia spinulosa
Adiposogenital dystrophy
Encephalocraniocutaneous lipomatosis
Pachyonychia congenita
Lipoatrophia annularis
Mandibuloacral dysplasia
Thanatophoric dysplasia
Genu recurvatum