Pachydermodactyly – Just a sign of emotional distress

ARTICLE

Auteur(s) : Helmut Beltraminelli, Peter Itin

Dermatology Department, University Hospital of Basel, Petersgraben 4, 4031 Basel, Switzerland

accepté le 29 Juillet 2008

The family of a fifteen year-old patient had noted a change in the form of his fingers since end of 2006 (figure 1). The third and fourth fingers, of the right hand more than the left hand, showed focal discrete swelling with slight epidermal changes, including scaling and some thickening (lichenification) of the skin (figure 2). The patient had no further symptoms, in particular no pruritus or burning or pain on his hands. We observed a repetitive manipulation of his hands during the medical consultation. The localisation of the swelling and thickening of the skin correlated with the zones of continuous rubbing (figure 3). Other clinical findings were a syndactyly on the left foot and a 5 × 4 cm nevoid hypertrichosis on the left lower back. No induration was felt and there was no synovitis, joint movement alterations or systemic manifestations.

In his personal history we found an orthopaedic problem of the left leg with coxa vara and, as a consequence, a stress-fracture of the tibia resulted. The histological analysis of a skin biopsy in January 2007 showed unspecific findings with hyper- and parakeratosis, acanthosis, slightly lymphocytic inflammation, and thickened vertical collagen bundles in the papillary dermis.

Discussion

PDD consists of asymptomatic, benign, circumscribed bulbous swelling of the lateral aspects of the proximal interphalangeal joints (PIP) of the fingers II-IV (figure 4); occasionally the dorsal or the ventral parts of the fingers are also involved. Sometimes the skin shows lichenification, fine desquamation or hyperkeratosis; a mild erythema is occasionally present [23]. Distal variants [24-26] and also painful variants [1, 27-30] have been reported rarely. As a rule the appearance is symmetric on both hands. Exceptionally, the fifth finger is affected as well; involvement of the thumb is unusual [31-33]. A few cases have been reported with localized PDD in only one finger [29, 34, 35]. In a few cases the lesions affected the region of the metacarpophalangeal joints and the dorsum of the hand: the term PDD transgrediens [30, 36, 37] was proposed. Toes are never affected; plantar pachydermia [38] was cited one time in a patient with acrocyanosis.

PDD usually affects otherwise healthy young patients with a mean age of 21.2 years with a male/female ratio of 3/2. PDD occurs as sporadic disease, only a few familial cases have been reported [24, 30, 33, 39, 40]. In one case [41] the father of a young patient presented knuckle pads.

There are no underlying bony anomalies, no synovitis or joint movement alterations. X-rays of the hands are normal. Magnetic resonance imaging (MRI) [6, 42] of patients with PDD shows typical fusiform soft tissue swelling around the PIP joints with sparing of the tendons and ligaments; there is no bone, periostal, capsular or articular involvement.

The clinical features of this unusual disease are sufficiently characteristic that the diagnosis can be established without a biopsy, especially if history of repeated mechanical traumatization or signs of a tic-like habit are present; nevertheless histologic findings can help to rule out other diseases with a similar appearance. A prompt clinical diagnosis would avoid unnecessary extensive investigations and inappropriate treatments.

PDD has been reported as a cutaneous sign of tuberous sclerosis [12, 30, 43], in association with carpal tunnel syndrome and Dupuytren’s contracture [44], gynecomastia [27], atrophodermia maculosa varioliformis cutis [45], Ehlers-Danlos syndrome [12], Asperger syndrome [46] and syndactyly of the foot (current case). Confusion with juvenile chronic arthritis has also been reported [47].

All these cited associations are probably comorbidities by chance and additional cases are necessary to identify a real statistically relevant relationship to another disease.

A classification of PDD was proposed by Bardazzi et al. in 1998 [30]. They suggested 5 types of PDD: (a) classical PDD, mostly in young men, affecting many fingers, frequently associated to mechanical stress of the skin; (b) solitary or localized PDD, being also sometimes of traumatic (mechanical) origin; (c) PDD transgrediens, with extension to metacarpophalangeal articulation and hand; (d) familial PDD; (e) PDD associated to tuberous sclerosis.

From the histopathological point of view, PDD is characterized by ortho- or parakeratotic hyperkeratosis, acanthosis, occasionally papillomatosis and/or hypergranulosis. The underlying dermis is thickened and sometimes shows a benign proliferation of fibroblasts and frequently large, haphazardly arranged collagen fibres entrapping the skin appendages and extending into the subcutaneous tissue. Elastic fibres are mostly reduced in numbers, thickened or thinned, sometimes fragmented. There is usually scant or no inflammation. Occasionally there is a deposition of mucin [48] in the deep dermis. The association of epidermal acanthosis with thickening of the dermis is unspecific but characteristic of PDD and is a useful criterion to differentiate it from other similar diseases such as keratoderma, where dermal thickening is not present, or from fibromatosis, which usually lacks epidermal changes.

Some authors [44, 49] documented an increase in collagen type III and V in a pattern typical of fibromatoses. Electron microscopy in some cases showed increased numbers of fine-diameter collagen fibres [30, 40, 49, 50].

The differential diagnosis includes many diseases (table 2): true knuckle pad, pseudo knuckle pad (PKP), chewing pads, collagenous plaques of the hands, juvenile digital fibromatosis, juvenile hyaline fibromatosis, progressive nodular fibrosis of the skin, thyroid disease, pachydermoperiostosis (Touraine-Solente-Golé syndrome), acromegaly, connective tissue nevi, fibrosing inflammatory conditions, Garrod pads in professional violinists, acropachydermodactyly in psoriasis, paraneoplastic acropachydermodactyly, spina ventosa, ostitis cystoides multiplex Jüngling, fibrous tumor of childhood, Thiemann’s disease, sarcomas, metastases, giant cell tumor of tendon sheet.

The true knuckle pads [51] are present in both men and women, localization is mostly on the dorsa of the proximal interphalangeal (PIP) joint areas and the lateral sites are usually not affected, some patients have coexisting fibromatoses (a.e Dupuytren’s); histology shows a fibroblast proliferation, giving the possibility of distinguishing it from PDD. Pseudo knuckle pads [3, 6, 52] (false knuckle pads) show an acquired form of localized callosity of the dorsal site of the phalanx after repeated trauma, as in children with obsessive-compulsive behaviour or as in occupational disorders; Wollina [53, 54] and Meigel et al. consider chewing pads as a separate entity, because the history, clinical presentation and localisation of the skin lesions differ from PDD and from PKP. It may be that the difference between PDD, PKP and chewing pads is simply the site of the trauma and the resulting localisation [55]; the medical terminology of different callosities is still confusing.

Degenerative collagenous plaques of the hands (synonymous with keratoelastoidosis marginalis and digital papular calcific elastosis) are progressive, sometimes calcifying, diseases. Juvenile digital fibromatosis shows histological pathognomonic eosinophilic juxtanuclear inclusion bodies (which express muscle actin) with myofibroblast proliferation, all changes which are not present in PDD. Juvenile hyline fibromatosis causes progressive subcutaneous nodules on the finger with consequent contractures, lytic bone lesions and ulcerations [56]. Progressive nodular fibrosis of the skin presents multilocalized progressive-growing tumoral nodules [57]. In hyperthyroidism manifestations, subcutaneous swelling of the metacarpal and proximal phalangeal region is often associated with pretibial myxedema, ophthalmopathy and periostal proliferation. Pachydermoperiostosis, a very rare genetic disease associated with seborrhoea, causes digital enlargement from a combination of pachydermia, periostosis and clubbing of the fingers, related to altered proteoglycan synthesis by fibroblasts [58]. Patients with acromegaly show excessive growing of many body parts, if considered as a differential diagnosis, serum growth hormone values help in the differential diagnosis. In Garrod’s pads there is a swelling of the distal interphalangeal area, especially in professional violinists [59]. Paraneoplastic acropachydermodactyly is easily ruled out in the absence of malignancy. In connective tissue nevi and sarcomas there is no history of tic-like behaviour and strict symmetrical localisation on the lateral fingers is, for both diagnoses, unusual. Thiemann’s disease (hereditary necrosis of the epiphysis) has an initially similar clinical appearance but shows progression with painful deformity of the fingers and limitation of function, X-rays are sometimes helpful for differential diagnosis [60]. Granuloma anulare, necrobiosis lipoidica, rheumatoid nodules, skin sarcoidosis and gout nodules are easily differentiated by clinical criteria. Giant cell tumors of the tendon sheet are mostly palmar and on the distal parts of the fingers, they are associated with an impairment of finger flexion and should be clinical easily differentiated from PDD.

Fibromatoses are idiopathic diseases with a progressive character and are usually not a consequence of chronic mechanic skin stimulation. From the histological point of view, fibrous overgrowths are a heterogeneous group of lesions with at one end fibroma, and at the other end fibrosarcoma, in between are the “fibromatoses”, which are defined as non-metastasizing, non-destructive fibrous tumors which tend to invade locally and recur after surgical excision [61, 62]. From a pathophysiological point of view fibromatoses are explained as fibroblast and myofibroblast proliferation during the acute phase and as cell-arm connective tissue thickening in later phases. Epidermal changes are not mentioned. Considering this definition of fibromatosis, although many authors previously called PDD a form of fibromatosis, we do not think that PDD belongs to this group of lesions. Basex et al. [1] also distinguish their newly described pachydermia from fibromatosis. From an ultrastructural point of view, the finding of increased collagen type III and V in PDD is not a confirmation of fibromatosis; in fact at the present time it is well known that collagen type III is increased in children, in embryonic and fetal tissue and the first phase of wound healing [63]; continuous rubbing of the skin leads to micro traumas of the dermis and an increase of collagen type III could be interpreted as a normal reaction of “wound healing”.

The fact that this diagnosis has been established mostly in male patients could be the consequence of hormonal triggering in puberty [44]. Like other authors who have described patients with PDD evidently associated with mechanical skin stimulation (table 1), we are convinced that true PDD is merely a consequence of exogenous factors, frequently in a tic-like manner such as rubbing and pressing, finger crossing or gripping. These ritualistic habits cause a friction mostly on the index, middle and ring fingers of both hands, explaining the sparing of the thumb and of the fifth finger.

Our opinion is supported by the literature data, where in 35% of the cases there is evidence of mechanical injury of the skin. The number could be even higher as of the remaining 65% not every author could definitely rule out mechanical skin irritation. As with other authors [40], it is our hypothesis that this kind of mechanical skin injury could be a consequence of tic-like behaviour or of emotional distress in general. Unfortunately, in the available literature, a mental disorder is mentioned only in a minority of reported cases and it seems also difficult to assess the validity of these diagnoses, which could sometimes be speculative. Therefore, to confirm our suspicion, we need some systematic studies of this topic, applying validated instruments to diagnose emotional distress in a relevant number of patients. Sometimes the observation of the mechanical friction is only possible after accurate surveillance of the patient by his/her family, as in the case cited by Basex [1]. Only after re-evaluation of the medical history, was the obsessive-compulsive behaviour found.

Callot et al. [45] discuss the role of repetitive mechanical stimulation, observing that microtrauma on the hands is very common and could hardly explain such an uncommon disease. In effect, it is our opinion that PDD is more common than anticipated so far. In behaviour-related conditions, there is often a grey zone between a simple tic and a pathological psychiatric disorder. Extreme tic forms can be considered a sign of emotional distress. Pseudo-knuckle-pads are now included in the list of psychocutaneous manifestations [64]. It is our opinion that PDD should also be included in the list.

Some other cases reported in the literature have an uncommon presentation and we intend to analyze some of those cases with the aim of discovering if they are really PDD, PCP or other diseases. Kouskoukis [33] describes a young man with “fibromatous tumors overlying the finger joints”, presented as pseudo knuckle pads with a possible hereditary character as the father of the patient had a similar clinical appearance; the description together with the pictures are in our opinion suggestive for the diagnosis of PDD. Okuyama [26] and Tompkins [25] describe two distinct older patients (80 and 65 years) with an uncommon condition affecting the volar and lateral parts of the distal phalanges of both hands. The first also combined similar fibrotic nodules on the elbows and a carpal tunnel syndrome, the second showed nail abnormalities, which have not been found in the cases of PDD reported so far; they propose it as PDD. In our opinion it must be another diagnosis. Yanguas et al. [37] report two cases of PDD, one of them shows a fibromatous thickening of the dorsal fingers extending to the dorsal aspect of both hands. Although he does not describe any mechanical stimulation of the skin, the histopathology with a hyperorthokeratosis and acanthosis suggest such a stimulus. Considering the particular localisation, it seems not to be a classical case of PDD, but taking into account the history it could be a variant of it with a similar pathogenetical mechanism. Krasovec et al. [65] discuss a possible analogy to scleroderma because of the fibroblast proliferation found in some cases. In our review of the literature we found only 9 cases with proliferation of fibroblasts and 7 of them are a series of the same author [30] and we do not think that PDD are a type of scleroderma.

A recent article reporting video game induced knuckle pads [66] (not considered in our table 1) reflect the ambiguity of the diagnosis of knuckle pads, being in adults a consequence of repeated mechanical injury of the skin, such as found in chicken hangers or boxers, and being mostly idiopathic in children, but accepting in children also the possibility of a repeated mechanical stimulation of the skin. As in PDD, there are many grey zones where different authors interpret a diagnosis and its pathophysiological mechanism.

There is no effective medical treatment for PDD, although intralesional triamcinolone resulted in a reduction of the swelling in some cases [67]. Localized subcutaneous resection had been performed in some patients who recovered without sequelae. In those patients in whom a traumatic aetiology was demonstrated, discontinuation of the mechanical traumatisation led to a marked amelioration of the finger swelling [16-19]. Emphasising the benign character of PDD, we suggest non-invasive treatment options. Psychological and psychosomatic approaches could be other options, particularly if the hypothesis of emotional distress as a cause of PDD is confirmed with systematic studies in the future.

In conclusion, we think that many similar disorders, which include PDD, PKP and chewing pads, are different diagnoses with different clinical presentations, but reflecting a spectrum of diseases with a similar mechanism of origin.
Table 1 Pachydermodactyly – Review of the literature

^*Some of the patients cited have OCD (not specified which one).

Table 2 Differential diagnosis of Pachydermodactyly

Acknowledgements

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