Keratoma sulcatumL08.8

Castellani, 1910

Globally widespread, bacterial, non-inflammatory infection of the sole of the foot, with swelling of the corneal layer, flat pitted corneal defects, which occur mainly in areas subject to mechanical stress.

Athletes and soldiers who wear occlusive footwear for long periods of time, or barefoot people who perspire heavily and spend time on wet surfaces, such as laborers, farmers and sailors, are more susceptible to this problem. Martial artists are at greater risk of skin infections due to constant physical contact, which can lead to the transmission of viral, bacterial and fungal pathogens, directly, but also indirectly through contact with infected sports mats and the skin flora of another infected person (Balić A et al. 2018).

Infection is particularly common in tropical and subtropical zones.

The manifestations of PK are due to superficial cutaneous infection caused by various bacterial gram-positive species, including:

Corynebacterium species

Kytococcus sedentarius

Dermatophilus congolensis

Actynomices keratolytica and

Streptomyces

which proliferate under suitable humid conditions and produce proteinases and sulfur compounds as byproducts (Balić A et al. 2018). Proteinases digest keratin and destroy the stratum corneum, resulting in the characteristic skin finding, while sulfur compounds (sulfides, thiols, and thioesters) are responsible for the foul odor.V.a. Kytococcus sedentarius, corynebacteria, Dermatophilus congolensis, Actinomyces spp.

The manifestations of "Pitted keratolysis" (PK) are due to a superficial cutaneous infection caused by various bacterial Gram-positive species, including:

• Corynebacterium species
• Kytococcus sedentarius
• Dermatophilus congolensis
• Actynomices keratolytica and
• Streptomyces.

These pathogens can multiply under suitable humid conditions. They produce proteinases and sulfur compounds as byproducts (Balić A et al. 2018). Proteinases digest the keratin and destroy the stratum corneum, resulting in the characteristic skin findings, while sulfur compounds (sulfides, thiols, and thioesters) are responsible for the characteristic, albeit foul, odor.This is especially true for Kytococcus sedentarius, Korynebacteria, Dermatophilus congolensis, and Actinomyces spp.

Worldwide distribution, frequently found in youthful sneaker wearers. People > 50 years are very rarely affected.

Predilection sites are soles of the feet, especially heel, ball of big toe, lateral parts of the sole.

Mostly challenging, penetrating odor of the "sweaty foot" (bromhidrosis) with pronounced hyperhidrosis. Characteristic is a whitish swollen horny layer with interspersed dimple-shaped, 0.1-0.3 cm large flat horny layer defects (pits) that appear as if punched out, which can confluence to form 1.0-3.0 -5.0 cm large, shallow, usually circularly limited depressions. Usually no tenderness on pressure. Sometimes, however, burning, stabbing pain is complained of during walking.

Circumscribed defects in the stratum corneum. PAS: no evidence of mycelia!

Careful daily foot washing or foot baths with disinfectant solutions (e.g. chlorhexidine solution 0.2%), soaps or syndets.

Alternative: Topical solutions containing erythromycin, clindamycin or clotrimazole.

General indications:

• Change stockings daily, no occluding footwear, wear breathable shoes.
• Use of antiperspirants containing methenamine (e.g. Antihydral ointment) or aluminium chloride hexahydrate R005 or R006 as well as perfumed or unscented deodorants to mask unpleasant foot odour.

The clinical combination of Trichobacteriosis axillaris with Keratoma sulcatum and Erythrasma is not very rare.

1. Balić A et al. (2018) Tatami Mats: A Source of Pitted Keratolysis in a Martial Arts Athlete? Acta Dermatovenerol Croat 26: 68-70.
2. Castellani A (1910) Keratoma plantare sulcatum. J Ceylon Br Med Assoc 1: 12-14.
3. Lee HJ et al (1999) Pitted keratolysis of the palm arising after herpes zoster. Br J Dermatol 140: 974-975
4. Longshaw CM et al (2002) Kytococcus sedentarius, the organism associated with pitted keratolysis, produces two keratin-degrading enzymes. J Appl Microbiol 93: 810-816
5. Rho NK et al (2008) A corynebacterial triad: prevalence of erythrasma and trichomycosis axillaris in soldiers with pitted keratolysis. J Am Acad Dermatol 58 (2 Suppl):S57-558
6. Takama H et al (1997) Pitted keratolysis: clinical manifestations in 53 cases. Br J Dermatol 137: 282-285
7. van der Snoek EM et al. (2013) Pitted keratolysis; physicians' treatment and their perceptions in Dutch army
8. personnel.J Eur Acad Dermatol Venereol 27:1120-1126
9. Wohlrab J et al (2000) Keratolysis sulcata (pitted keratolysis): clinical symptoms with different histological correlates. Br J Dermatol 143: 1348-1349
10. Zaias N et al (1965) Pitted keratolysis. Arch Dermatol 92: 151-154