DR8.1-5 | Common Viral Infections — Glossary

A nucleoside analogue antiviral active against herpesviruses (HSV, VZV); the mainstay of treatment, most effective when started early.

Treatment that restores immunity in HIV; the key intervention for extensive molluscum in HIV, since topical/physical treatments alone are often ineffective without immune recovery.

Self-spread of HPV from one site to another (e.g. by scratching), seeding new warts; the basis of the Koebner pattern in warts.

T-lymphocyte-based immune defence that controls intracellular pathogens including viruses; when it wanes (ageing, HIV, immunosuppression), latent viruses reactivate and infections become more extensive.

The small central dimple in a molluscum papule — the key recognition feature distinguishing it from warts and milia.

A rash pattern denser on the trunk than the limbs, characteristic of varicella (chickenpox).

A focal area of protective hyperkeratosis over a pressure point; skin lines run through it, there are no black dots, and it is tender on lateral pressure — the key differential from a plantar wart.

Destruction of a wart by freezing with liquid nitrogen; a first-line in-clinic treatment for viral warts.

A deep fungal infection that, in HIV, can produce umbilicated papules mimicking molluscum; biopsy of atypical/progressive lesions excludes it.

A physical treatment in which molluscum papules are scraped off with a curette.

The normal surface skin lines; in a wart they are interrupted (stop at the lesion's edge), whereas in a corn they run through the lesion.

The area of skin supplied by a single spinal nerve root; herpes zoster is confined to one dermatome and does not cross the midline.

The classic description of the varicella vesicle — a clear, thin-walled vesicle sitting on an erythematous base.

Disseminated HSV infection superimposed on eczematous skin — a dermatological emergency requiring prompt antiviral therapy.

Antiviral treatment taken at the onset of each herpes recurrence to shorten and attenuate the episode.

A thread-like, finger-shaped wart, typically perioral, perinasal or on the eyelids.

Molluscum lesions larger than 1 cm, characteristically seen in HIV/immunocompromised patients and a clue to immunosuppression.

The defining morphological signature of herpes simplex (and other herpesvirus skin lesions): a cluster of small vesicles sitting on a red base.

Large eosinophilic cytoplasmic inclusion bodies (molluscum bodies) seen in keratinocytes infected by molluscum contagiosum virus.

Large eosinophilic cytoplasmic inclusion bodies in keratinocytes infected by MCV — the histological hallmark of molluscum contagiosum.

Recurrent herpes simplex on or near the vermilion border of the lip — the common cold sore; grouped vesicles preceded by a tingling prodrome.

A herpesvirus causing grouped vesicles on an erythematous base; HSV-1 typically causes orolabial (herpes labialis) and HSV-2 typically causes genital infection, though either site can be affected by either type.

Reactivation of latent VZV producing a unilateral, dermatomal band of grouped vesicles that does not cross the midline, often preceded by dermatomal pain.

Herpes zoster involving the ophthalmic division of the trigeminal nerve; sight-threatening and requiring urgent ophthalmology referral.

A family of enveloped DNA viruses that establish lifelong latency in nerve ganglia and periodically reactivate; the skin-relevant members are herpes simplex virus (HSV-1, HSV-2) and varicella zoster virus (VZV).

The herpes simplex virus type that classically causes orolabial infection (herpes labialis/cold sores), though it can also cause genital infection.

The herpes simplex virus type that classically causes genital herpes, though it can also cause orolabial infection.

A non-enveloped DNA papillomavirus that infects keratinocytes and causes warts (verrucae); it does not establish ganglion latency and spreads by direct contact and autoinoculation.

A topical immunomodulator that stimulates a local immune response; useful for plane warts and some other warts.

Virus-encoded mechanisms that locally suppress the host immune response, allowing molluscum lesions to persist and to become extensive when immunity is poor.

An injectable cytotoxic agent used for resistant or recalcitrant warts.

The appearance of lesions along lines of trauma or scratching; seen with HPV warts (and other dermatoses), reflecting spread by autoinoculation.

A keratinocyte with a perinuclear clear halo, the histological hallmark of HPV (wart) infection.

The state in which a herpesvirus genome persists silently in a sensory ganglion after primary infection, without producing virus, until reactivation occurs.

Tiny white keratin cysts without a central dell and not infectious — a differential from molluscum.

A common, benign poxvirus skin infection presenting as pearly, dome-shaped papules with a central umbilication (dell).

A poxvirus that replicates in the keratinocyte cytoplasm and causes pearly, umbilicated papules; it has no systemic antiviral and is often self-limiting in immunocompetent hosts.

An eczematous reaction in the skin surrounding molluscum lesions, sometimes the reason a patient presents.

A plaque formed by multiple plantar warts coalescing together.

The cytological hallmark of herpesvirus infection seen on a Tzanck smear, formed by virus-induced fusion of infected epidermal cells.

A deep, tender type of plantar wart (often HPV-1) with a characteristic dome shape; a recognised plantar-wart variant.

Polymerase chain reaction detection of HSV DNA — the gold-standard investigation, able to confirm infection and distinguish HSV-1 from HSV-2.

Polymerase chain reaction detection of VZV DNA — the gold-standard test, able to confirm infection and distinguish VZV from HSV.

The presence of lesions in several different stages at the same time — the key feature distinguishing varicella from smallpox (where lesions are synchronous).

Dermatomal neuropathic pain persisting more than three months after the onset of the zoster rash; incidence and severity rise with age.

A topical destructive agent applied to molluscum lesions to induce resolution; a commonly used home/clinic option.

A large DNA virus that, unusually, replicates entirely in the host-cell cytoplasm using its own enzymes; MCV is the skin-relevant member.

The severe first (primary) orolabial HSV infection, typically in young children, with extensive painful oral vesicles/ulcers, fever and lymphadenopathy.

The warning sensation of tingling, burning or itching that precedes a recurrent herpes simplex eruption by about 24–48 hours.

Herpes zoster of the geniculate ganglion causing facial palsy with vesicles in the ear and ipsilateral facial weakness.

The re-emergence of a latent herpesvirus from a ganglion, travelling back along the nerve to the skin to produce a recurrent lesion, triggered by fever, UV exposure, stress or immunosuppression.

Localised, briefer HSV episodes at the same site, preceded by a prodrome and usually without systemic symptoms — distinct from severe primary infection.

A topical keratolytic agent, suitable for home use, that is a first-line treatment for viral warts.

A deeper, larger, non-umbilicated nodule — a differential from molluscum.

An infection transmitted by sexual contact; genital molluscum in adults is regarded as an STI and warrants screening for other STIs.

Daily antiviral treatment used to reduce the frequency of recurrences in patients with frequent or severe recurrent herpes.

The single, painless, indurated genital ulcer of primary syphilis — a critical differential from the painful grouped vesicles/erosions of genital herpes.

Tiny clotted dermal capillaries seen as black dots within a wart — a key recognition feature absent in corns.

A rapid bedside cytology test from the base of a fresh vesicle; multinucleate giant cells indicate a herpesvirus (HSV or VZV) but do not distinguish which one.

The central dimple or dell seen in molluscum contagiosum papules, a key recognition feature distinguishing them from warts.

An oral prodrug of aciclovir with better bioavailability and simpler dosing; an alternative first-line antiviral for herpes simplex.

Primary VZV infection: a centripetal, itchy eruption whose hallmark is lesions in different stages (macule, papule, vesicle, crust) present simultaneously.

A herpesvirus that causes varicella (chickenpox) on primary infection and herpes zoster (shingles) on later reactivation from dorsal root ganglia.

A hyperkeratotic, verrucous epidermal papule caused by HPV, often showing thrombosed capillaries (black dots) and interrupted skin lines.

Small, flat-topped, skin-coloured to light-brown papules, often multiple on the face and dorsa of hands, frequently arranged in lines from Koebnerisation.

An inward-growing (endophytic) wart on the sole that is painful on direct pressure and shows central black dots; the mosaic variant is several coalescing plantar warts.

A firm, rough, exophytic hyperkeratotic papule with a cauliflower surface and black dots, typically on the dorsum of the hands, fingers and periungual skin.

A benign hyperkeratotic epidermal growth caused by human papillomavirus, characterised by interrupted skin lines and black dots (thrombosed capillaries).

A legitimate management choice for warts, since many resolve spontaneously as cell-mediated immunity develops, particularly in children.

A vaccine (live-attenuated or recombinant subunit) given to older adults to reduce the incidence of herpes zoster and post-herpetic neuralgia.