Successful Resolution of Pachydermodactyly in an Adolescent Boy

Children presenting with musculoskeletal findings have a large number of differential diagnoses, including inflammatory and noninflammatory conditions.¹ Pachydermodactyly is a rare condition that may mimic chronic inflammatory arthritis of childhood.^2,3 We present an adolescent boy with pachydermodactyly that shows a resolution of the condition with appropriate treatment.

A 16-year-old boy with a 4-year history of gradual and painless swelling of the fingers of both hands was referred to the Pediatric Rheumatology Clinic with a suspicion of inflammatory arthropathy. He was asymptomatic but defined a compulsive joint cracking related to anxiety. Family history did not indicate any rheumatic or autoimmune diseases. Physical examination revealed swelling localized around the lateral and dorsal aspects of the proximal interphalangeal joints and proximal phalanges of the second, third, and fourth fingers without any signs of inflammation (Figure 1A). Manual muscle testing was normal. Facial tics and an anxiety disorder were diagnosed during psychological evaluation. Complete blood cell count, serum biochemistry, and thyroid function tests were within normal limits. Acute phase reactants, anti-nuclear antibody (ANA), rheumatoid factor (RF), cyclic citrullinated peptide antibodies (anti-CCP), and human leukocyte antigen B27(HLA-B27) were negative. Plain radiograph and magnetic resonance imaging (MRI) showed periarticular and periosseous soft tissue enlargement. No signs of synovitis and tendinitis were detected. After the diagnosis of pachydermodactyly, a nonsteroidal anti-inflammatory drug (naproxen) was given for 2 months. Physical exercise programs for range of motion, tendon gliding, and intrinsic strengthening for the fingers, and habit reversal training for joint cracking were provided for 6 months. A 6-month follow-up revealed almost complete resolution of pachydermodactyly (Figure 1B).

Figure 1.

Photographs of the right hand at (A) first admission and (B) 6-month follow-up.

Pachydermodactyly is a rare acquired digital fibromatosis that can be misdiagnosed as inflammatory arthropathy, sometimes leading to unnecessary diagnostic tests and treatments.^4,5 It is typically characterized by asymptomatic progressive periarticular swelling, mostly in bilateral hands sparing the first and fifth digits.⁶ A few cases with unilateral involvement have been shown.^3,5,7 To date, around 150 cases have been reported in the literature with a predominance of adolescent boys; however, underdiagnosis is possible due to its benign nature.⁸ Recurrent trauma to the fingers is a common underlying factor.^9,10 Due to increased recurrent mechanical trauma to fingers, a relationship with Ehler–Danlos syndrome, tuberous sclerosis, and Asperger’s syndrome has been found.^11,12 Furthermore, emotional distress and anxiety are important contributors to tic-like behaviors affecting the fingers.¹³ The absence of inflammatory symptoms such as morning stiffness and pain, normal laboratory tests without elevated acute phase reactants, and negative autoantibodies including ANA and RF are important to rule out other causes. Additionally, radiographs, ultrasound, and MRI identify soft tissue swelling without signs of synovitis.¹⁴ Histopathologic examination reveals increased deposition of collagen in the periarticular dermis that is predominantly structurally abnormal, and hyperkeratosis and acanthosis.⁸ Nevertheless, the biopsy might not be necessary if typical features are present and other causes are excluded. Although there is no consensus on treatment, discontinuation of recurrent trauma and psychological assessment are critical. Intralesional corticosteroid injections and corrective surgery have been used.^14,15 Prognosis is generally good, although one case was reported to present with deforming pachydermodactyly.¹⁶ Our case benefited from a comprehensive rehabilitation approach for improving the range of motion and intrinsic strengthening of fingers and a habit reversal training program targeting joint cracking behavior, initiated concurrently with short-term anti-inflammatory therapy. Upon the 6-month follow-up, a notable improvement was observed with almost complete resolution of pachydermodactyly.

By presenting this case, we hope to raise awareness of this uncommon condition and provide a follow-up that demonstrates how anti-inflammatory treatment, physical therapy, and behavioral therapy led to an almost complete remission.