You are in: eMedicine Specialties > Dermatology > BACTERIAL INFECTIONS Pitted KeratolysisArticle Last Updated: Sep 25, 2008AUTHOR AND EDITOR INFORMATIONSection 1 of 11
  Author: Joseph C English III, MD, Clinical Vice-Chairman for Quality and Innovation, Associate Professor of Dermatology, Department of Dermatology, University of Pittsburgh Joseph C English, III, is a member of the following medical societies: American Academy of Dermatology and American Medical Association Editors: James W Patterson, MD Director of Dermatopathology, Professor of Pathology and Dermatology, Departments of Pathology and Dermatology, University of Virginia Medical Center; David F Butler, MD, Professor of Dermatology, Texas A&M University College of Medicine; Chair, Department of Dermatology, Director, Dermatology Residency Training Program, Scott and White Clinic; Edward F Chan, MD, Clinical Assistant Professor, Department of Dermatology, University of Pennsylvania School of Medicine; Catherine Quirk, MD, Clinical Assistant Professor, Department of Dermatology, Brown University; Dirk M Elston, MD, Director, Department of Dermatology, Geisinger Medical Center Author and Editor Disclosure Synonyms and related keywords: keratoma plantare sulcatum, keratolysis plantare sulcatum, Micrococcus sedentarius, M sedentarius, Kytococcus sedentarius, K sedentarius, Dermatophilus congolensis, D congolensis, Corynebacterium species, Actinomyces species INTRODUCTIONSection 2 of 11
  BackgroundPitted keratolysis is a skin disorder characterized by crateriform pitting that primarily affects the pressure-bearing aspects of the plantar surface of the feet and, occasionally, the palms of the hand as collarettes of scale. The manifestations are due to a superficial cutaneous bacterial infection. Pitted keratolysis has gone through several name changes. It was described initially in the early 1900s as keratoma plantare sulcatum, a manifestation of yaws. It was identified in the 1930s as a unique separate clinical entity, and the name was changed to keratolysis plantare sulcatum. The current name, pitted keratolysis, describes the clinical presentation well. PathophysiologyPitted keratolysis is caused by a cutaneous infection with Micrococcus sedentarius1 (now renamed to Kytococcus sedentarius), Dermatophilus congolensis,2 or species of Corynebacterium and Actinomyces. Under appropriate conditions (ie, prolonged occlusion, hyperhidrosis, increased skin surface pH), these bacteria proliferate and produce proteinases that destroy the stratum corneum, creating pits.3 K sedentarius has been found to produce 2 keratin-degrading enzymes. They are protease P1 (30 kd) and P2 (50 kd).4 The malodor associated with pitted keratolysis is presumed to be the production of sulfur-compound by-products, such as thiols, sulfides, and thioesters. In 2006, foot odor without pitted skin changes was discovered to be from isovaleric acid produced by Staphylococcus epidermidis, a normal skin flora.5 FrequencyUnited StatesPitted keratolysis occurs worldwide. It can be seen in both tropical and temperate environments. A study of 142 homeless men in the Boston area revealed that 20.4% of 142 examined patients had pitted keratolysis.6 InternationalPrevalence rates have ranged from 1.5% of 4325 Japanese industrial workers to 2.25% (11 of 490 subjects randomly evaluated) in New Zealand. In the tropical military setting, where heat, humidity, and boots combine to produce a microenvironment that predisposes to this disease, prevalence rates are much higher. Of the 387 volunteer soldiers evaluated in South Vietnam, 53% had pitted keratolysis. Recently, in Britain, 25 of 184 examined athletes had pitted keratolysis. In 341 paddy field workers in costal South India, 42.5% had pitted keratolysis.7 Mortality/MorbidityNo mortality is associated with pitted keratolysis. However, the excessive foot odor from this disorder may be socially unacceptable. Pitted keratolysis may be symptomatic; producing secondary painful feet, which can limit function. In 2005, in Turkey (East region), a study of dermatologic manifestations in 88 hepatitis B surface antigen carriers compared with 84 controls demonstrated a significantly higher prevalence of oral lichen planus and pitted keratolysis. The mechanism is unknown and further studies are needed to confirm this association.8 RaceNo race predilection is reported. SexTheoretically, both males and females should be affected; however, most written case reports or studies have involved male patients. AgePitted keratolysis can affect patients of any age. CLINICALSection 3 of 11
HistoryThe patient with pitted keratolysis may complain of malodor, hyperhidrosis, sliminess, and, occasionally, soreness or itching associated with the pits9; however, the pits normally are asymptomatic. The etiology of the tenderness in symptomatic cases of pitted keratolysis is unknown. In addition to pits, erythematous to violaceous macules to plaquelike lesions may be present.10 In military personnel, whose long-term occlusive boot wearing exacerbates disease, lesions often become denuded, leading to foot pain and disability.11 The palms of the hand also have been reported to be involved in some patients with pitted keratolysis of the feet. Here, a collarette forms around the keratolysis, rather than pits. A triad of concurrent corynebacterial diseases (ie, erythrasma, trichomycosis axillaris, and pitted keratolysis) has been reported.12 In a 2008 study, 108 of 842 South Korean male soldiers were diagnosed with pitted keratolysis, of which 13 of 108 (13%) had the triad.13 Clinicians making a diagnosis of pitted keratolysis need to examine the patient for evidence of other corynebacterial infections. PhysicalThe primary lesions of pitted keratolysis are pits in the stratum corneum ranging from 0.5-7 mm, with some development of confluence, irregular erosions, or sulci (see Media File 1). A variant of markedly enlarged lesions, called crateriform pitted keratolysis, also has been described.14 This affects the entire width of the plantar surface of the foot underlying the metatarsophalangeal joints. The pits rarely are seen on non–pressure-bearing areas of the plantar surface. CausesSee Pathophysiology. DIFFERENTIALSSection 4 of 11
Tinea Pedis
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| Drug Name | Clindamycin (Cleocin) |
|---|---|
| Description | Lincosamide for treatment of serious skin and soft tissue staphylococcal infections. Also effective against aerobic and anaerobic streptococci (except enterococci). Inhibits bacterial growth, possibly by blocking dissociation of peptidyl tRNA from ribosomes causing RNA-dependent protein synthesis to arrest. Many clinicians find topical antibiotics to be effective, even without other measures. They are easy to use and well accepted by patients. Either solution or gel formulations may be used. |
| Adult Dose | Apply topically bid |
| Pediatric Dose | Apply as in adults |
| Contraindications | Documented hypersensitivity |
| Interactions | None reported |
| Pregnancy | B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals |
| Precautions | Superinfections may occur with prolonged or repeated antibiotic therapy |
| Drug Name | Erythromycin (E.E.S., E-Mycin, Ery-Tab) |
|---|---|
| Description | Inhibits bacterial growth, possibly by blocking dissociation of peptidyl tRNA from ribosomes causing RNA-dependent protein synthesis to arrest. For treatment of staphylococcal and streptococcal infections. In children, age, weight, and severity of infection determine proper dosage. When bid dosing is desired, half-total daily dose may be taken q12h. For more severe infections, double the dose. |
| Adult Dose | Topical: Apply bid to affected area Oral: 250 mg erythromycin stearate/base (or 400 mg ethylsuccinate) PO q6h, or 500 mg q12h (1 h ac or 2 h pc); alternatively, 333 mg PO q8h; increase to 4 g/d depending on severity of infection |
| Pediatric Dose | Topical: Apply as in adults Oral: 20 mg/kg PO 2 h prior to procedure, followed by 10 mg/kg 6 h after initial dose |
| Contraindications | Documented hypersensitivity; hepatic impairment |
| Interactions | Coadministration may increase toxicity of theophylline, digoxin, carbamazepine, and cyclosporine; may potentiate anticoagulant effects of warfarin; coadministration with lovastatin and simvastatin increases risk of rhabdomyolysis |
| Pregnancy | B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals |
| Precautions | Caution in liver disease; estolate formulation may cause cholestatic jaundice; GI side effects are common (give doses pc); discontinue use if nausea, vomiting, malaise, abdominal colic, or fever occur |
| Drug Name | Mupirocin (Bactroban) |
|---|---|
| Description | Inhibits bacterial growth by inhibiting RNA and protein synthesis. |
| Adult Dose | Apply thin film to affected area 2-5 times/d for 5-14 d |
| Pediatric Dose | Administer as in adults |
| Contraindications | Documented hypersensitivity |
| Interactions | None reported |
| Pregnancy | B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals |
| Precautions | Prolonged use may result in the growth of nonsusceptible organisms |
Instruct the patient to return to the clinic if therapy is unsuccessful. Otherwise, care proceeds on an as needed basis.
Pitted keratolysis is cured easily and has an excellent prognosis.
Educate the patient about the etiology of the disorder and regarding ways to prevent and treat pitted keratolysis. See Medical Care.
Failure to make the correct diagnosis is the only area in which a health care provider may find difficulty with a patient with this disorder. Patients may complain of undue mental anguish due to foot odor from pitted keratolysis, which could have resolved easily with proper identification and treatment of the disorder.
| Media file 1: Classic pitted keratolysis on the plantar surface of the foot. | |
 | View Full Size Image | Media type: Photo |
| Media file 2: Histopathology reveals a crater limited to the thick stratum corneum of the epidermis. | |
 | View Full Size Image | Media type: Photo |
Article Last Updated: Sep 25, 2008
