Pachydermodactyly: bilateral proximal interphalangeal joint swelling in an adolescent musician

Abstract

An otherwise healthy young man was referred to the rheumatologist because of bilateral proximal interphalangeal (PIP) joint enlargements. The main concern was excluding the presence of inflammatory arthritis. Physical examination revealed bilateral PIP finger joints (II-IV) swellings and cutaneous thickenings in adjacent areas. The specificity of this case was the patient who appeared in the physician’s room with his violin suitcase pointing to his profession even from the first site. Complete blood count with leucocyte differentials appeared without changes. Radiographics failed to show joint fluid or bony changes. All immunological markers (RF, anti-cyclic citrullinated peptide) and laboratory data (Erythrocyte sedimentation rate, C-reactive protein, etc) were within the reference ranges or negative. After exclusion of rheumatoid and other inflammatory arthritis, and considering the occupation of the patient and demographics the diagnosis of a rare condition–pachydermodactyly was made.

Background

Pachydermodactyly is a rare cause of proximal interphalangeal joint swelling. It commonly presents in young men.¹ Identifying this condition and proper differential diagnosis is important, as it keeps patients away from unnecessary investigations and treatment.

Case presentation

A man in his late teens was referred to the rheumatologist, because of bilateral finger joint enlargements.

The patient noted swellings on his fingers 2 years ago, which then gradually worsened over this time. Physical examination findings were notable only for bilateral proximal interphalangeal swellings present in the second, third, and fourth fingers of both hands, as well as cutaneous warts on the left second and the right third and fourth fingers as shown in figure 1. All hand joints bilaterally had a normal range of motion and no local tenderness was present in the palpated areas. Anamnesis was negative for morning stiffness, or any kind of rash, and the patient’s only complaint was intermittent, low-grade pain surrounding fingers mainly after violin classes. When asked about his violin classes the patient, pointing to his violin suitcase (which was with him when he entered the physician’s room), said that this was his main interest for the past 5 years. He attends violin classes three times per week and each class lasts 2 hours. Apart from these symptoms he considers himself otherwise healthy and denies any other repetitive or habitual activity involving his fingers or hands. His parents were healthy without similar findings, and his family history was negative for any joint disorders and neuropsychiatric conditions.

Figure 1.

Swellings on right and left second to fourth PIP joints. Cutaneous warts on the left second and right third and fourth fingers.

Investigations

Complete blood count including all inflammatory markers and CRP was within normal range. Immunological analysis for rheumatoid factor, antinuclear antibodies and anti-CCP was negative. Liver and renal function tests (Alanine aminotransferease, Aspartate aminotransferease, and bilirubin) and (creatinine, urea and uric acid), respectively, were unremarkable. The X-ray of both hands was unremarkable, showing normal bones, absence of erosions or joint narrowing. Ultrasonography showed non-homogenous thickening of periarticular soft tissues and swellings most commonly in the areas of PIP of the fingers. There were no fluids or synovial hypertrophy in the metacarpophalangeal, proximal interphalangeal and distal interphalangeal joints. The bones were without erosions or osteophytes. The flexor tendons of the fingers had no thickness, were homogenous, and had no fluid around the tendons. Ultrasound findings are shown in figure 2.

Figure 2.

Ultrasound findings.

The biopsy was offered but had not done due to the patient’s preferences.

Differential diagnosis

Having normal complete blood analysis with normal or negative immunological markers, considering radiographic findings and the classic second to four bilateral PIP joint involvement the diagnosis of pachydermodactyly was made.²

Treatment

The patient was informed about the benign nature of his disease and that there are no universally accepted treatment options at this time. He was advised to take Non-steroidal anti-inflammatory drugs (NSAIDs) as needed, and cut-off his violin classes if possible, considering the literature review about the possible occupational nature of this condition. For cutaneous warts, a referral to the dermatologist was made.

Outcome and follow-up

After the diagnosis of pachydermodactyly, the follow-up appointment was scheduled for 2 months, and the patient was advised to contact whenever there will be any additional signs, symptoms or joint problems.

Discussion

The first described case of pachydermotactyly was in 1973 by Bazex et al,³ later this condition acquired its name by J Verbov in 1975.⁴ This benign condition is characterised by bilateral periarticular soft tissue swellings, and subsequent enlargements typically around PIP joints of second to fourth fingers. When a biopsy is done, it almost always shows deposition of fibroblasts and collagen to a variable extent.⁵ The cause of this rare and benign disorder is still unknown, and documented cases until today point to associations with habitual hand and finger using, for example, avid video gamers or occupational activities which repetitively cause minor injuries such as various sports, rock climbing and food processing.^5–7 Various psychological and behavioural conditions such as obsessive-compulsive disorder and generalised anxiety disorder are other suggested causes.^{8 9} According to the systematic review carried out by Fernandez et al, out of 139 patients, only 6 reported musical instrument playing in the past, without any specifiers or details about frequency or duration of activity.¹⁰ The diagnosis is mainly clinical and focused on ruling out other causes, especially juvenile idiopathic, rheumatoid and other inflammatory arthritis.¹¹ Although there is no worldwide accepted treatment for this benign condition, some specialists made trials with glucocorticoid injections and/or surgery with various successes.^12–14

Our case presented with classic signs and demographics of pachydermotactyly. It appeared to have a strong occupational basis, in a musician who is an avid violinist. Taking the rarity of this condition, medical professionals should carry a great sense of suspicion for the identification of this condition.

Learning points.

• Bilateral PIP joint swellings are not always arthritis and do not always need to be treated.

• In otherwise healthy young men, presenting with bilateral PIP joint swelling, after excluding the most common causes, one should think about pachydermodactyly.

• Diagnosis is important as it limits a patient’s anxiety and spares unnecessary investigations and treatments.

• While making the diagnosis one should be attentive to the details pointing to some sort of repetitive activity causing microtraumas, the cause of which can be a violin.

Ethics statements

Patient consent for publication

Consent obtained directly from patient(s).