Vivian Balassiano, M.D.
Celso Tavares Sodré, M.D.
Marcia Ramos-e-Silva, M.D., Ph.D.

Rio de Janeiro, Brazil

From the Section of Dermatology
HUCFF-UFRJ - School of Medicine
Federal University of Rio de Janeiro

Summary
We report a case of pachydermodactyly, rare entity characterized by acquired diffuse swelling of back and sides of the fingers.

Key words: collagen, connective tissue, fibroblasts, fibroma, fibrosis, pachydermodactyly, skin diseases.

Bazex et al. 1, in 1973, observed a "very curious hypertrophy of the lateral aspects of the proximal phalanges", which could not be classified as any of the previously known syndromes and suggested the possibility of a new entity. It was only two years later that pachydermodactyly was described by Verbov 2, initially as a variant of true knuckle pads, in a 19-years-old male patient that showed diffuse swelling over the dorsal and lateral aspects of the proximal interphalangeal joints of some fingers. The lesions were asymptomatic and the biopsy revealed hyperkeratosis and acanthosis overlying a dermis with increased amounts of fibrous tissue. Since then, 21 new cases were reported, just two of which were females 3, 4. All these cases, as well as the presently reported, are shown in Table I.

CASE REPORT
A 12-years-old black female student, born in Rio de Janeiro, Brazil, had a two years history of progressive swelling of fingers, specially over the proximal interphalangeal joints of the second, third and fourth fingers of both hands. The lesions of the right hand were more pronounced. They were symptomless and freely movable. The overlying skin of several lesions showed lichenification (Fig. 1 and 2). Clinical examination, including the toes, was otherwise unremarkable. There was no family history of the disorder, trauma nor exaggerated manual activities. There was an achromic nevus on the right thigh, since birth.

The undertaken laboratorial examinations were normal, including blood cell count, sedimentation rate, biochemistry, serum proteins, anti-nuclear factor, anti-DNA, latex, Waaler-Rose and complement. Both hand's X-rays showed soft tissue swelling with no bony abnormalities.

The histopathologic examination showed, on hematoxylin-eosin, hyperkeratosis, acanthosis and very discrete perivascular mononuclear inflammatory reaction (Fig. 3). Masson trichrome, orcein and colloidal iron stainings revealed normal collagen and elastic fibers and also no deposits of connective tissue mucin.

DISCUSSION
Pachydermodactyly is a rare form of digital acquired fibromatosis, characterized clinically by swelling of the soft tissues over the interphalangeal joints in their dorsal and lateral aspects. The clinical features are diagnostic, since they are highly specific, even without a biopsy.5 Pachydermodactyly fulfills the criteria for fibromatosis described by Stout,6 which are: proliferation of cytologically benign fibroblasts, abnormal accumulation of collagen fibers and an infiltrative pattern of growth. Of the 21 previously reported cases 1, 2, 3, 4, 5, 7, 8, 9, 10, 11, 12, 13, 14, 15 (Table I), one was associated with Dupuytren's contractures and carpal tunnel syndrome5, one with tuberous sclerosis10 and one with knuckle pads14. All the cases began in puberty or right after (Table I).

Histologically, in hematoxylin-eosin stain, there is hyperkeratosis, hypergranulosis, discrete hyperplasia of the epidermis and deposits of collagen, connective tissue mucin, and slight proliferation of blood vessels thickening the dermis. There is an increase in the number of fibroblasts.3

Draluck et al.,3 using special stains, observed, in Masson trichromic, an increased number of thick and thin collagen fibers; in Verhoeff-van Gieson, decreased numbers of elastic fibers that were thinned and elongated in the fibrous proliferation that surrounded adnexal structures; and in colloidal iron, increased deposits of connective tissue mucin. These authors also performed a panel of immunohistochemical stains that confirmed the fibroblastic derivation.

Biochemical studies revealed increased concentration of Type III collagen and a small amount of Type V collagen. Electron microscopy shows decreased diameter of the collagen fibers in reticular dermis.5

The differential diagnosis has to be made with knuckle pads,16 a localized, circumscribed digital fibrosis, which can be related to trauma. Histologically, there is hyperkeratosis, orthokeratosis, acanthosis and dermal inflammatory infiltrate.17 In contrast to the histology of knuckle pads, pachydermodactyly does not present orthokeratosis associated to exuberant acanthosis, instead, there is hypergranulosis and thickening of the dermis with extension of collagenous fibers into the subcutaneous tissues.

The etiology of pachydermodactyly is unknown. Reichert et al.5 relate the increased of collagen type III, a fetal-embryonic-type collagen, to the beginning of the disease during puberty. The etiologic relation with trauma was not established in the twelve cases reported until now. There is no successful therapy, but Curley et al.8 reported that intralesional injections of steroids may improve the clinical appearance.

REFERENCES
1. Bazex A, Dupré A, Teillard J. Pachydermie digitale des premières phalanges par
hyperplasie conjonctive dermique et aplasie hypodermique. 1973;
2. Verbov J. Pachydermodactyly: a variant of the true knuckle pad. Arch Dermatol 1975;
111:524.
3. Draluck JC, Kopf AW, Hodak E. Pachydermodactyly: first report in a woman. J Am
Acad Dermatol 1992;27(2 pt 2):303-5.
4. Bardazzi F, Fanti PA, de Padova MP, Varotti C. Localized pachydermodactyly in a
woman. Acta Derm Venereol (Stockh) 1994;74(2):152-3.
5. Reichert CM, Costa J, Barsky SH et al. Pachydermodactyly. Clin Orthop 1985;
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6. Stout AP. Juvenile fibromatosis. Cancer 1954;7:953.
7. Fleeter TB, Myrie C, Adams JP. Pachydermodactyly: a case report and discussion
of the pathologic entity. J Hand Surg 1984;9A:764-6.
8. Curley RK, Hudson PM, Marsden RA. Pachydermodactyly: a rare form of
digital fibromatosis. Report of four cases. Clin Exp Dermatol 1991;16:121-3.
9. Sola A, Vazquez-Dova J, Sola J, Quintanilla E. Pachydermodactyly trangrediens. Int J Dermatol 1992;31(11):796-7.
10. Lo WL, Wong CK. Localized pachydermodactyly in tuberous sclerosis. Clin Exp
Dermatol 1993;18(2):146-7.
11. Iraci S, Bianchi L, Innocenzi D, Tomassoli M, Nini G. Pachydermodactyly: a case of
an unusual type of reactive digital fibromatosis (letter). Arch Dermatol
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12. Hagedorn M, Graf HG, Grosshans E. Pachydermodaktylie. Folge einer wangsneurose.
Hautarzt 1994;45(2):88-90.
13. Lautenschlager S, Itin PH, Rufli T. Pachydermodactyly: reflecting obsessive-compulsive behavior? Arch Dermatol 1994;130(3):387.
14. Yanguas I, Goday JJ, Soloeta R. Pachydermodactyly: report of two cases. Acta Derm Venereol 1994;74(3):217-8.
15. Brousse C, Rybojad M, Piette AM, Gepner P, Chapman A. La pachydermodactylie: une observation. Rev Med Interne 1994;15(6):412-4.
16. Ramos-e-Silva J. Coussinets des phalanges "Pulvillus digiti". Ann Derm Syph 1956;82:22-33.
17. Morginson WJ. Discrete keratodermas over the knuckle and finger articulations. Arch
Dermatol 1955;71:349-53.

Table I. Clinical features of all reported cases of pachydermodactyly.

Fig. 1: Lesions on both hands, more pronounced on the right.
Fig. 2: Right hand of patient. Observe the swelling of fingers with lichenification, specially over the proximal interphalangeal joints of the second, third and fourth fingers.
Fig. 3: Histopathology of the lesion (HE 40X).