K | Basicmedical Key

kalanchoe leaves herbal remedy for treatment of verruca (see Table C9)

Kaltostat highly absorbent calcium and sodium alginate wound dressing; forms a hydrophilic gel with wound exudate, maintaining a moist wound interface and preventing tissue maceration (see Table D10)

Kaposi’s sarcoma rare, virus-induced, tumour of vascular endothelium; affects elderly Jewish or middle-European men, and the immunosuppressed (it is especially aggressive in human immunodeficiency virus [HIV]-positive cases); presents in skin as multiple, well-circumscribed purple macules, e.g. of lower eyelids

KE20 white elastomer putty, mixed with a catalyst; used to form orthodigita or prosthetic toes

Kelikian push-up test see test, Kelikian push-up

Keller’s procedure first-ray arthroplasty to correct hallux rigidus; i.e. excision of proximal one-third of proximal phalanx of hallux, and first metatarsal head exostoses

keloid exuberant hypertrophic scarring, due to genetic trait, especially in African races

kelvin see scale, kelvin

keratin sulphur-containing, insoluble scleroprotein, forming stratum corneum, nail plate and hair shaft, from enzymic conversion of epidermal cells

keratinization enzymic conversion of epidermal skin cells to keratin

keratinocytes basal-layer epidermal cells, daughter cells of which move towards the exterior whilst undergoing gradual enzyme degradation to form keratin; their function includes forming cytoskeleton filaments and desmosomal connections, immune function, cutaneous inflammation and tissue repair (through cytokine secretion [e.g. interleukins, interferon, tumour necrosis factor-alpha] following tissue injury or in certain skin diseases)

keratoacanthoma rapid-growing, localized skin tumour; i.e. central mass of skin surface keratin which invades the dermis; undergoes spontaneous resolution

keratoderma blenorrhagicum psoriasis-like, yellowish, hyperkeratotic lesions of plantar skin; characteristic of late-stage Reiter’s disease

keratolysis separation or loosening of stratum corneum to form intraepidermal blisters (compare with acantholysis)

keratolytics topical agents that break down keratin (by breaking intermolecular bonds and causing maceration); assist removal of tough, outer stratum corneum, and penetration of keratolytic or caustic medicaments to deeper tissues, e.g. 10+% salicylic acid (see caustics; and Table C9, Table K1)

Table K1 Keratolytic and caustic agents

Keratolytic/caustic agent	Indicated use
Whitfield’s ointment (3% salicylic acid and 6% benzoic acid in white soft paraffin)	Treatment of mild tinea pedis
5% salicylic acid ointment	Applied daily for 7 days to soften hyperkeratosis and facilitate its removal
12% salicylic acid in collodion	Macerating agent; painted over callosity and left in situ for 7 days, to assist removal of heavy callosity
20–40% salicylic acid plaster	Applied topically and left in situ for 1–2 days to aid removal of corns
40–70% salicylic acid ointment	Applied topically in a cavitied pad and left in situ for 7 days for verruca treatment; the lesion should be masked
Calmurid cream (10% urea)	To hydrate anhidrotic skin; applied daily to treat dyskeratosis
40% urea cream	A strongly keratolytic agent, applied under an occlusive dressing and left in situ for 7 days, to soften, macerate and aid the reduction and removal of hypertrophied nails in patients who are unsuitable for nail avulsion
Monochloroacetic acid	A deeply penetrating caustic that is painful in use Applied, retained in situ and reviewed within 3–7 days, for the treatment of verrucae: 1. as a saturated solution to the lesion 2. as a tiny crystal strapped over a masked lesion 3. as a tiny crystal embedded in 40–70% salicylic acid retained by a cavitied pad
Trichloroacetic acid	A self-limiting caustic with a superficial action Applied directly to the verruca, after initial scalpel debridement of the lesion May be used in conjunction with 75–95% silver nitrate (see below) as a diagnostic or a final treatment of verrucae
75–95% Silver nitrate	A self-limiting caustic with a superficial action, causing a dark brown discoloration of the skin to which it is applied; it is used for the treatment of shallow or mosaic verrucae. Note: Some patients show an idiosyncratic local sensitivity or inflammatory reaction to applied silver nitrate 1. Applied directly to the lesion, after overlying callosity has been debrided off 2. Applied directly to the lesion in alternating layers with trichloroacetic acid 3. As a diagnostic aid to identify verrucous tissue; viral-infected skin cells show up as bright white dots within a few moments of the application of the layers of silver nitrate and trichloroacetic acid
Potassium hydroxide (KOH)	A powerful keratolytic caustic with a great affinity for water that penetrates deeply dissolving precipitated protein; used to destroy soft tissues 1. Overlying hyperkeratosis is debrided off the verruca and the foot is immersed in water for 5 minutes to hydrate the skin, then dried; a KOH pellet is rubbed into the lesion; the foot is reimmersed in water and the jelly-like material formed by the KOH on the lesion surface is debrided off. The process is repeated once or twice until the lesion appears to have gone, then glacial acetic acid is applied to neutralize the KOH 2. A similar protocol may be used to ablate nail matrix after removal of the overlying section of nail plate 3. KOH 5% liquid applied to heavy callosity and left in situ for 5 minutes softens heavy callosity to ease its removal
Pyrogallol (pyrogallic acid)	A powerful analgesic, non-self-limiting, caustic reducing agent. It may be used in the treatment of recalcitrant verrucae or neurovascular corns in areas of skin overlying a healthy layer of fibrofatty padding. It should only be used with great caution as its action continues after application has ceased and can lead to severe tissue breakdown that is slow to heal. It is incompatible with alkalis, iron salts, oxidizing agents and ammonium salts 1. 20% pyrogallol ointment for the treatment of neurovascular corns 2. 40% pyrogallol ointment for the treatment of VP 3. WP ointment (20% pyrogallol, 20% wheat germ oil) for the treatment of tough, fibrous, hyperkeratotic plantar lesions
Phenol	An analgesic, corrosive caustic. It is used as an 80% solution (liquefied phenol) to destroy soft-tissue lesions such as VP, or nail matrices (three applications, each of 1 minute duration). Its action is quenched by dilution with IMS or isopropyl alcohol. Healing is delayed for several weeks after its application
Glacial acetic acid	A weakly acidic mild caustic that is crystalline at 14°C 1. As a paint to hard or vascular corns, or VP (return period 14–21 days) 2. As a paint to VP, alternating with silver nitrate 75% (in a similar manner to trichloroacetic acid) 3. To neutralize KOH (see above: KOH, point 1)
Nitric acid	A powerful analgesic oxidizing caustic agent with a superficial action that offers a ‘one-off’ VP treatment 1. Applied to VP with a glass rod and left in situ for 5 minutes, followed by phenol solution 10%; the skin stains bright yellow 2. The lesion is saturated with phenol solution 5% for 5 minutes, then with nitric acid for 20–30 seconds, then once again with phenol solution 5%
Strong iodine solution (iodine solution 10%; iodine fortis)	A strong astringent and vesicant agent. It is incompatible with many topical medicaments, and can cause sensitivity reactions in some patients 1. to shrink nail tufts 2. to shrink hypergranulation tissue
Formaldehyde	A strongly astringent and antiseptic agent used in the treatment of VPs (the skin surrounding the lesion should be protected with petroleum jelly; sensitivity is likely) 1. 10% formaldehyde in collodion, painted on daily 2. 36% formaldehyde solution, painted on daily
*Thermal caustics*
Cryosurgery	The topical application of liquid nitrogen (at −196°C) or nitrous oxide (at −88.5°C) to destroy small soft-tissue lesions; the cell cytoplasm must be reduced to and maintained at −24°C or lower for at least 1 minute, and repeated for two further freezing episodes between which the area has been allowed to thaw. Cryosurgery is more effective when any overlying hyperkeratosis is removed before freezing
Hyfrecation	Tissue destruction by initial fulguration (outlining and superficial charring) of the lesion by the application of high-frequency electrical energy), then electrodesiccation (electrocautery) of the lesion by the release of electrical energy whilst the probe is inserted into the lesion
Electrosurgery	Tissue removal using high-frequency energy waves to incise through tissue