Interphalangeal pads on pachydermodactyly

Abstracts

Coxins interfalangeanos são nodulações ceratósicas, de limites precisos, com aproximadamente um centímetro de diâmetro, geralmente sobre as articulações interfalangenas das mãos. A paquidermodactilia é uma tumefação uniforme da pele que ocorre nas falanges proximais das mãos. É relatado o caso de um jovem com associação de paquidermodactilia e coxins interfalangeanos, fato não encontrado na literatura médica. Embora haja descrição que considera serem essas manifestações diversas da mesma doença, acredita-se que sejam entidades distintas. O ato compulsivo de atritar a pele parece ser o denominador comum mais aceito para justificar as duas doenças. Os autores postulam que o coxim interfalangeano seria uma resposta epidérmica, enquanto a paquidermodactilia, uma resposta dérmica a um mesmo fator traumático sobre a pele. O paciente foi tratado com infiltração intralesional de triancinolona, com melhora clínica expressiva das duas manifestações.

dedos; fibrose

CASE REPORT

Interphalangeal pads on pachydermodactyly^*

José Marcos Pereira^I; Fernanda Corrêa Netto Pereira^II; Vivian Corrêa Netto Pereira^II

^IEx- Professor of Dermatology, School of Medicine, Santa Casa, São Paulo

^IIMedical Students at the Metropolitan University of Santos

^{Correspondence}

SUMMARY

Knuckle pads are keratotic nodulations within precise limits and approximately one centimeter in diameter, usually on the interphalangeal joints of the hands. Pachydermodactyly is a uniform swelling of the skin occurring in the proximal phalanges of the hands. A case involving a young man suffering from several knuckle pad lesions concomitant with pachydermodactyly was studied. This association has not been previously described in the literature. Although it has been reported that both conditions are different manifestations of the same disease, they are believed to be distinct disorders. The compulsive act of rubbing the skin seems to be a common denominator mostly accepted as the cause of both diseases. The authors affirm that knuckle pads may be acquired as an epidermal response, while pachydermodactyly, is a dermal response to the same traumatic factor to the skin. The patient was treated with intralesional infiltration of triamcinolone resulting in a remarkable clinical improvement in both manifestations

Keywords: fingers; fibrosis

INTRODUCTION

Interphalangeal pad (IP), also frequently known as knuckle pads and pachydermodactyly (PD) are two dermatoses that have been the subject of few studies. According to Verbov,¹ who created the term PD in 1975, the two entities could represent different clinical manifestations of the same disease.

IPs are hyperkeratose nodulations, with a rough surface, slightly brownish or grayish and about one centimeter in diameter. In general they are round, hardened and present precise limits and regular outlines. They are asymptomatic and the clinical course is chronic. The most frequent locations are the proximal interphalangeal and metacarpophalangeal articulations. They are less frequent in the other articulations of the fingers and rarely occur in the toes.

The histopathology is very characteristic with hyperkeratosis, acanthosis and prolongation of the papillary crests.¹⁵ Psoriasiform acanthosis,²² proliferation of the capillaries and fibroblasts,⁹ perivascular inflammation and increase in the bands of collagen in the dermis have also been observed.²²

The first publication was made in 1893 by Garrod,² who described three patients with dorsal nodulations on the fingers. Since one of the patients presented Dupuytren's contracture and another had a grandfather also with contracture, the author associated the nodulations to Dupuytren's contracture. In 1904, the same author³ made a detailed study on the disease, and used the term pads in 12 cases, of which six had Dupuytren's contracture. The classic denomination of knuckle pads was created by Jones,⁴ in 1923. IP was known during the Renaissance, because it is clearly depicted in the works of Michelangelo, Vasari, Bronzino and Durer.⁵

The disease has already received countless designations, including heloderma, tylositas articuli, subcutaneous fibroma, keratosis supracapitularis, coussinets des phalanges, pulvillus digiti, Garrod's pads, discreet keratoderma, benign tumor of the chorion, fibrochondroma, congenital hypoplasia and cojinetes articulares laterales.

Since the publication of Garrot,² approximately 335 cases have been described.^2-29 There is a male sex bias (56%), with ages ranging from five to 69 years. Familial cases of IP have also been described.^8,23

Only the work by Mikkelsen¹⁴ has described the incidence of IP in the population. In 1977, the author, examined 1,871 normal people (752 men and 1,119 women), aged between 20 and 89 years, in the city of Haugesund (Norway) and found 164 presented IP, of which 68 were men (9.0%) and 96 (8.6%) women, or in other words, approximately 9% of the population and the disease was most frequent among those over 40 years.

IP is associated to several alterations, including dysfunction in the metabolism of vitamin A,¹³ fibrodysplasia, palmoplantar keratoses and ichthyosis,⁹ deafness and leukonychia (familial cases),^11,25 pseudoxanthoma elasticum¹⁰ and acrokeratoelastoidosis;²⁸ the most frequent association, however, is with the Dupuytren's contracture. Caroli and cols.²¹ examined 352 patients with Dupuytren's contracture (318 men and 34 women) and found IP in 54 (15.3%), of which 51 were men (95.3%) and three women (5.5%). In another work, Mikkelsen¹⁴ examined 869 patients with Dupuytren's contracture (623 men and 246 women), found 385 with IP, of which 303 were men (48.7%) and 82 women (33.3%), showing a very high incidence of IP in patients with Dupuytren's contracture.

The etiopathogenesis of IP is still unknown. According to Ronchese³⁰ CI is part of the so-called Touraine's peripheral fibromatosis, which includes Dupuytren's contracture, induratio penis plastic (Peyronie's disease), cutaneous fibromas and scleroderma. Caroli and cols.²¹ consider that Dupuytren's contracture and CI are expressions of the same fibromatous alteration, since fibroblasts, myofibroblasts, macrophages and extracellular matrix are findings common to both diseases.

Lagier and cols.¹² classify IP into two forms: false or pseudo-IP, resulting from attrition and represented by acanthosis and hyperkeratosis; and true IP, characterized by a proliferation of fibroblasts in the dermis. Sehgal and cols.¹⁵ divided the disease into two types: Primary IP (asymptomatic) and secondary (symptomatic), which could be associated to Dupuytren's contracture, palmoplantar keratosis, ichthyosis or professional trauma. Trauma certainly seems to have a great influence on the onset of IP; consequently, it is frequently associated to work.³¹ Richards and cols.¹⁸ eexamined 41 workers in a poultry slaughterhouse and found 23 presented IP. While in the offices of the same company, they examined 41 employees and no cases of IP were found. The disease is also observed frequently in pugilists²⁷ and violinists.¹⁹ In children there is a prevalence of the idiopathic form, while in adults the IP originates from trauma.²⁹

Patients with IP usually consult the dermatologist for aesthetic reasons, however there is no specific treatment for the disease. Some cases in childhood disappear spontaneously by adult age,¹⁷ though this in general does not occur with the idiopathic form. Regarding IP of traumatic origin, remission of the lesion can occur following removal of the attrition.²² Several types of therapy have been attempted, including 50% phenol and cryotherapy,⁷ rsurgical excision²⁰ and occlusion with silicone gel;²⁴ however, recurrence is frequent.

Pachydermodactyly (PD) is a thickening of the skin of the fingers, mainly close to the proximal phalanges. It is most common in adolescents.

The first description of this disease was made in 1973, by Bazex,³² in a 23-year-old man and denominated it pachidermie digitale des primières phalanges. In 1975, Verbov¹ presented the case of a man aged 19 years and called the picture pachydermodactyly. Although the patient of Verbov did not present IP lesions, due to the histopathology characterized by hyperkeratosis, acanthosis and increase in fibrous tissue in the dermis, the author postulated that PD could be a variant of IP.

PD has also been denominated pachyderma, discreet keratoderma, hyperkeratose-acanthosis and fibromatosis.

Since the first publication on PD, approximately 50 cases have been described in the literature,^1,32-62 of which 77.5% involved males and the remaining 22.5% were female. The majority of patients were between 14 to 29 years of age, although cases have been reported among patients as young as 5 and as old as 63 years. The disease duration was up to 15 years.

In the majority of cases PD involves the second, third and fourth fingers of both hands. A case has been described of a women with the disease in a single finger.⁴² there can be lichenification of the skin in the lesion,³⁹ erythema and desquamation^38,40 and, in some cases, the lesion can be painful.^32,37,57 The process can extend to the metacarpophalangeal articulations, configuring PD transgrediens.⁴⁰ There are reports of familial cases with lesions in the mother and daughter⁴⁸ and in sisters.⁵⁷

The classic histopathology shows hyperkeratosis, acanthosis, intense thickening of the dermis due to an increase in the fibroblasts and deposits of collagen. Staining by Alcian blue reveals a mucin deposit.^{37,39,40,42,47,57} An increase can also be observed in the thickness of the basal membrane,³³ augmented eccrine sudoriparous glands, various of which are fibrose, and intense deposit of mucopolysaccharides,³⁴ poor demarcation between the papillary and reticular dermis,³⁵ marked eosinophilia³⁶ and lymphocytic infiltrate.³⁷

Histochemical study of the collagen fibers showed them to be collagen I, III and V. Under electron microscopy the collagen fibers are finer than those of normal tissues.^35,59

The etiopathogenesis of PD is unknown. Some authors consider it is due to compulsive neuroses, in which patients rub the fingers of one hand against those of the other.^44,50

PD has already been described associated to Dupuytren's disease,³⁵ carpal tunnel syndrome,³⁵ ginecomastia,³⁷ varioliform macular atrophy,⁵⁵ juvenile chronic arthritis, thyroid dysfunction, seborrheic dermatitis and glossitis,³⁴ tuberous sclerosis,^46,57 Ehlers-Danlos syndrome.⁵⁷ However, the most frequent association is with repetitive trauma.^{41,44,50,61,62}

Baldazzi and cols.⁵⁷ cclassified PD into five main forms: 1 - classic form (associated to trauma); 2 - localized form or monopachydermodactyly; 3 - transgressing forms (dorsal region of the hands); 4 - familial; and 5 - symptomatic, associated to tuberous sclerosis.

The differential diagnosis should be made between:³⁶ pachydermoperiostosis; acropachydermodactyly in psoriasis, multiple osteitis cystica, fibrous tumor, acromegaly, chronic juvenile arthritis, synovitis, rheumatoid nodules, gouty tophus, xanthomatosis, fibrosarcomas, juvenile fibromatosis, Heberden's nodes and lichen myxedematosus.

Various therapies have been attempted for PD, including surgical removal,^34,61 intralesional infiltration with triamcinolone^36,37,56 and reducing the attrition by controlling the compulsive neurosis.^44,50,62

In Brazil, no case of PD has been registered. Rutowitsch & Lima⁶² described CI in a girl.

The objective of this work was to report the association of CI with PD, a which has hitherto not been described in the literature, and the excellent result with the therapeutics instituted for both diseases.

CASE REPORT

MVNS, 17 years old, male, white, born in São Paulo, SP, presented complaining of swelling in the fingers of the hands and small nodules in the skin with onset eight years previously. Dermatological exam showed an increase in the volume of the fingers, mainly in the area of the proximal phalange, involving the second to fifth fingers of both hands (Figures 1 and 2). The alteration was asymptomatic, however it totally impeded flexing of the fingers, which hindered certain daily activities. Several keratose and nodular lesions were observed, with precise limits, on the metacarpophalangeal articulations and lateral face of the tumefaction (Figure 3). The patient himself affirmed that the lesions were caused by attrition, because he constantly crossed and rubbed the fingers of one hand against the other. Although the hyperkeratose lesions were also asymptomatic, the patient scratched them frequently. Furthermore, he reported that the video game control was another factor of attrition. Anatomicopathological exam was done on a spindle shaped specimen, including at the same time the nodular lesion and edematous area (Figure 4). The epidermis presented acanthosis and hyperkeratosis (corresponding to the nodulation). In the dermis there was a numeric increase in the fibroblasts, proliferation and thickening of the collagen fibers were also observed, involving the eccrine sudoriparous glands. The collagen fibers were dissociated by the presence of mucin. There was no inflammatory process. X-ray of the hands did not reveal any involvement of the bones or periostea. The clinical and histological diagnosis was interphalangeal pad on pachydermodactyly. The patient was counseled to avoid rubbing his fingers the fingers and perform biweekly sessions of intralesional infiltration with triamcinolone in the PD and under the IP. There was a total disappearance of the CI lesions and a practically total normalization of the skin in the area of PD (Figures 5 and 6) together with an ample recovery in the finger movement. After one month of follow-up, there were no indications of recurrence.

DISCUSSION

The authors classify the patient as having the classic form of PD, according to the definition of Baldazzi and cols.,⁵⁷ and secondary CI, according to Sehgal and cols.¹⁵ Neither the patient nor his relatives presented indications of Dupuytren's contracture. It was evident that the patient's clinical manifestations were of traumatic origin.

Although the patient of Verbov¹ had PD without the characteristic lesions of IP, due to the histopathological findings he considered PD to be a type of clinical manifestation of IP. In all the literature consulted, this is the only description that considers both alterations as being part of the same disease.

To date, approximately 335 cases of IP and 50 of PD have been described, demonstrating that they are clinically distinct diseases, IP presenting histological alterations that are eminently epidermal, and PD dermal alterations. There was no description regarding a simultaneous occurrence of both diseases. Except for the patient described by Yanguas and cols.,⁴⁵ athat presented PD and apparently had a single IP lesion, as observed in the photograph, however the authors did not make any mention to this fact in the text.

It seems there can be no doubt that both diseases are triggered, or at least aggravated, by some compulsive rubbing action of the skin. The authors consider that both diseases are two different responses to the same etiological agent.

Patients can have different cutaneous responses to attrition of the skin. For instance, a patient that frequently scratches a lesion can present a predominantly epidermal reaction, forming a neurodermatitis. While another with pruritus and consequent itch, can have a dermal response, forming a keloid scar.

The case described here, besides PD, presented several lesions of metacarpophalangeal IP, some of which were on the PD itself, or in other words, on the lateral face of the fingers, showing that following rubbing his skin, the patient had concomitant epidermal and dermal responses, forming IP and PD, respectively. Returning to the previous example, it is as if the patient had developed a neurodermatitis on a keloid scar, a fact that has already been observed several times by the authors.

The patient was effectively clinically cured by understanding the problem and avoiding rubbing his hands together with intralesional infiltration with triamcinolone. There was a total recovery in the movement of the fingers.

We consider that the two entities are much more frequent than reported in the literature. A closer observation of all the ways that the skin can suffer attrition, whether due to compulsive neuroses or repetitive movements in the workplace, and a study of each individual's form of reaction should clarify the etiopathogenesis of both diseases and, consequently, lead to the development of an effective treatment.

ACKNOWLEDGEMENT

The authors thank Professor Nilceo S Michalany M.D. for performing the anatomicopathological exams.

REFERENCES

Received in July, 30^th of 2002.

Approved by the Consultive Council and accepted for publication in February, 11^th of 2003.

• 1. Verbov J. Pachydermodactyty: a variant of the true knuckle pad. Arch Dermatol 1975;111:524.
• 2. Garrod AE. On na unusual form of nodules upon joints of the fingers. St Bartholomew's Hospital Report 1883; 29:157-161.
• 3. Garrod AE. Concerning pads upon the finger joints and their clinical relationships. Brit Med J 1904; II: 8.
• 4. Jones HW. Two cases of Knuckle pads. Br Med J 1923; I:759.
• 5. Ramos e Silva J. Coussinets des phalanges (pulvillus digit). Ann Dermatol 1956; 83:22-33.
• 6. Carol WLL, Prakken JR, Zwijndregt HA. Tylositas articuli. Acta Dermatolvenereologica. 1940; 21:87-97.
• 7. Wise F. Knuckle pads. Arch Dermatol Syphilol. 1944;49:144-145.
• 8. Veltman G. Etiology of Knuckle pads. Dermatologica 1954; 108:20-33.
• 9. Allison Junior JR, Allison JR. Knuckle pads . Arch Derm 1966; 93:311-316.
• 10. Stankler L. Pseudoxanthoma elasticum with a knuckle pad on the thumb. Acta derm-venereol 1967; 47:263-266.
• 11. Bart RS, Pumphrey RE. Knuckle pads , leukonichia and deafness. N Engl J Med 1967; 276:202-207.
• 12. Lagier R, Meinecke R. Pathology of Knuckle pads. Virchows Arch A Path Anat Histol 1975;365:185-191.
• 13. Morginson WJ. Discrete keratodermas over the knuckle and finger articulations. Arch Dermatol 1955; 71:349-353.
• 14. Mikkelsen OA. Knuckle pads in Dupuystren's disease. The Hand 1977; 9:301-305.
• 15. Sehgal VN, Singh M, Saxena MHK, Nayar M. Primary knuckle pads . Clin Exp Dermatol 1979;4:337-339.
• 16. Kouskoukis CE. Stump the experts. J Dermatol Surg Oncol 1985; 11:209 e 349.
• 17. Paller AS, Hebert AA. Knuckle pads in children. AJDC 1986; 140:915-917.
• 18. Richards TB, Gamble JF, Castellan RM, Mathias CGT. Knuckle pads in live-chicken hangers. Contact Dermatitis 1987; 17:13-16.
• 19. Bird HA. Development of Garrod's pads in the fingers of a professional violinist. Ann Rheum Diseases 1987;46:169-170.
• 20. Marino JM,Vilar ML, Pozo T, Quinones PA. Cojinetes articulares laterales: una localización atípica de knuckle pads. Actas Dermo Sifilog 1990;81:473-474.
• 21. Caroli A, Zanasi S, Marcuzzi A, Guerra D, Cristiani G, Ronchetti IP. Epidemiological and structural findings supporting the fibromatous origen of dorsal knuckle pads . J Hand Surg (Brit) 1991; 16:258-262.
• 22. Mackey SL, Cobb MW. Knuckle pads . Cutis 1994; 54:159-160.
• 23. Ramer JC,Vasily DB, Ladda RL. Familial leuconychia, knuckle pads , haring loss na palmoplantar hyperceratosis. J Med Genet 1994; 31:68-71
• 24. Guberman D, Lichtenstein A, Vardy DA. Knuckle pads. A forgotten skin condition: report of a case and review of the literature. Cutis 1996; 57:241-242.
• 25. Kose O, Baloglu H. Knuckle pads, leukonychia and deafness. Int J Dermatol 1996;35:728-729.
• 26. Irwin LR, Naylor IL, Holms W. The contractility of knuckle pads. J Hand Surg(Brit) 1997; 22:110-112.
• 27. Kanerva L. Knuckle pads from boxing. Eur J Dermatol 1998; 8:359-361.
• 28. Abulafia J, Vignale RA. Degenerative collagenous plaques of the hands and acrokeratoelastoidosis: pathogenesis and relationship with knuckle pads . Int J Dermatol 2000; 39:424-432.
• 29. Peterson CM, Barnes CJ, Davis LS. Knuckle pads: does knuckle cracking play an etiologic role. Pediatric Dermatology 2000; 6:450-452.
• 30. Ronchese F. Knuckle pads and similar looking disorders. G Ital Dermatol Venereol 1966; 107:1227-1236.
• 31. Hueston JT, Wilson WF. Knuckle pads. Aust NZ J Surg 1973;42:274-277.
• 32. Bazex A, Dupré A, Teillard J. Pachydermie digitale des premieres phalanges par hyperplasie dermique et aplasie hypodermique. Bull Soc Fr Dermatol Syphiligr 1973;80:455-458.
• 33. Garrel J, Sonneck JM, Neveux Y, Millet P, Doss N, Lanternier G. Pachydermie digitale isolée. Ann Dermatol Venereol 1982; 109:769-770.
• 34. Fleeter TB, Myrie C, Adams JP. Pachydermodactyly: a case report and discussion of the pathologic entity. J Hand Surgery 1984;9:764-766.
• 35. Reichert CM, Costa J, Barsky SH, Claysmith AP, Liotta LA, Enzinger FM, Triche TJ. Pachydermodactyly. Clin Orthopaed Rel Res 1985;194:253-257.
• 36. Hudson PM. Pachydermodactyly. Br J Dermatol 1989; 121:111.
• 37. Curley RK, Hudson PM, Marsden RA. Pachydermodactyly: a rare form of digital fibromatosis - report of four cases. Clin Exp Dermatol 1991;16:121-123.
• 38. Martin JC, Rennie JAN, Kerr KM. Pachydermodactyly: confused with JCA. Ann Rheum Dis 1992; 51:1101-1102.
• 39. Draluck JC, Kopf AW, Hodak E. Pachydermodactyly: first report in a woman. J Am Acad Dermatol 1992;27:303-305.
• 40. Sola A, Doval JV, Sola J, Quintanilla E. Pachydermodactyly transgrediens. Int J Dermatol 1992; 31:796-797.
• 41. Iraci S, Bianchini L, Innocenzi D, Tomassoli M, Nini G. Pachydermodactyly: a case of an unusual type of reactive digital fibromatosis. Arch Dermatol 1993;129:247-248.
• 42. Bardazzi F, Fanti PA, Padova MP, Varotti C. Localized pachydermodactyly in a woman. Acta Derm Venereol (Stockh) 1994;74:152-153.
• 43. Meunier L, Pailler C, Barneon G, Meynadier J. Pachydermodactyly or acquired digital fibromatosis. Br J Dermatol 1994; 131:744-746.
• 44. Lautenschlager S, Itin PH, Rufli T. Pachydermodactyly: reflecting obsessive-compulsive behavior? Arch Dermatol 1994; 130:387.
• 45. Yanguas I, Goday JJ, Soloeta R. Pachydermodactyly: report of two cases. Acta Derm Venereol (Stockh) 1994;74:217-218.
• 46. Lo WL, Wong CK. Localized pachydermodactyly in tuberous sclerosis. Clin Exp Dermatol 1993; 18:146-147.
• 47. Rai A. An unusual case of peri-articular soft tissue finger swelling in na adolescent male: pachydermodactyly or pachydermoperiostose? Br J Rheum 1994;33:677-679.
• 48. Russo F, Pichardo RP, Camacho F. Familial pachydermodactyly. Acta Derm Venereol 1994; 74:386-387.
• 49. Brousse C, Rybojad M, Piette AM, Gepner P, Chapman A. Pachydermodactyly: report of a case. Rev Med Interne 1994;15:412-414.
• 50. Hagedon M, Graf HG, Grosshans E. Pachydermodactyly: sequela of obsessive nurosis. Hautarzt 1994; 45:88-90.
• 51. Dupin N, Gautier MS, Rabary G, Beltzer-Garelly E, Binet O. Pachydermodactyly. Ann Dermatol Venereol 1994;121:632-634.
• 52. Perez B, Gomez MI, Sanchez E, Munoz E, Ledo A. Pachydermodactyly: a case report. J Dermatol 1995;22:43-45.
• 53. Kopera K, Soyer HP, Kerl H. An update on pachydermodactyly and a report of three addicional cases. Brit J Dermatol 1995;133:433-437.
• 54. Costa MM, Romeu JC, Costa T. Pachydermodactyly a rare cause of finger joint swelling. J Rheumatol 1995;22:2374-2375.
• 55. Callot V, Wechsler J, Hovnanian A, Revuz J. Pachidermodactyly and atrophia maculosa varioliforme cutis. Dermatology 1995;190:56-58.
• 56. Kim TH, Cho YH, Park HB. Two cases of pachydermodactyly. J Dermatol 1996; 23:419-424.
• 57. Bardazzi F, Neri I, Fanti PA, Patrizi A. Pachydermodactyly in two woung girls. Pediatr Dermatol 1996;13;288-291.
• 58. Cartier H, Guillet MH, Schollhammer M, Guillet G. Pachydermodactylie de l'adolescent: expression d'un mal-être? Arch Pédiatr 1996;3:1091-1094.
• 59. Kang BD, Hong SH, Kim IH, Kim WK, Oh CH. Two cases of pachydermodactyly. Int J Dermatol 1997; 36:768-772.
• 60. Bardazzi F, Neri I, Raone B, Patrizi A. Pachydermodactyly: seven new cases. Ann Dermatol Venereol 1998; 125:247-250.
• 61. Aoki K, Iida H, Umeda T, Katayama I, Nishioka K. A case of pachydermodactyly. Jpn J Plast Reconstr Surg 1994; 37:109-113.
• 62. Aloi F, Solaroli C, Tomasini C. Pachidermodattilia e cursinetti delle falangi: dermatosi autoprovocanti? G Ital Dermatol Venereol 1993;128:393-397.
• 61. Itin PH, Lautenschlager S. Pachydermodactyly: a psychocutaneous disorders. Dermatology 1995;190:1-3.
• 62. Rutowitsch M, Lima LAF. Coxim interfalangeano. An Bras Dermatol 1971; 46:361-368.

*

Work done at "Centro Dermatológico de Guarulhos".

Publication Dates

• Publication in this collection
  03 Aug 2004
• Date of issue
  May 2004

History

• Received
  30 July 2002
• Accepted
  11 Feb 2003