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Abstract

  1. Top of page
  2. Abstract
  3. CASE REPORT
  4. DISCUSSION
  5. REFERENCES

Psoriatic onycho-pachydermo periostitis (POPP) is recognized as a rare subset of psoriatic arthritis, characterized by psoriatic onychodystrophy, connective tissue thickening above the distal phalanx, and a periosteal reaction. Therapy for this rare disease is based on treatments used for psoriatic arthritis, but traditional disease-modifying antirheumatic drugs, such as sulfasalazine and methotrexate, have shown inconsistent and unsatisfactory results. We report herein a successful therapeutic approach for POPP using the fully human anti–tumor necrosis factor (TNF) antibody adalimumab in a 42-year-old male patient. After 4 months of anti-TNF treatment, a remarkable normalization of the clinical appearance was achieved and magnetic resonance imaging showed complete resolution of the initial inflammatory lesions. Therefore, we consider a TNF-blocking strategy as promising for treatment of POPP.

Psoriatic onycho-pachydermo periostitis (POPP) is a recently described entity that consists of psoriatic onychodystrophy and connective tissue thickening above the distal phalanx, including a periosteal reaction (1). Together, these lesions result in a typical drumstick-like deformity of the digits. POPP can be extremely painful and frequently causes significant functional impairment. It has been recognized as an uncommon subset of psoriatic arthritis and, to date, only 15 cases have been described worldwide (1–12). Therapy for this rare disease is based on experiences with treatment of psoriatic arthritis but, according to the few published case reports, nonsteroidal antiinflammatory drugs and sulfasalazine showed inconsistent and unsatisfactory results (1–3). Methotrexate provided some benefit in only 3 reported cases (4, 5, 9). In this report, we describe the successful treatment of POPP using adalimumab, fully human monoclonal antibody that blocks tumor necrosis factor (TNF).

CASE REPORT

  1. Top of page
  2. Abstract
  3. CASE REPORT
  4. DISCUSSION
  5. REFERENCES

The patient, a 42-year-old man, had an 18-month history of painful swelling and onycholysis that affected all toes. Additionally, he had experienced inflammatory back pain for the last 6 months and intermittent pain in the right knee. His general medical history was unremarkable and there was no sign of intestinal or urogenital infection. As a metal worker who had to wear safety boots, the patient was severely affected by the painful lesions of his toes and was unable to perform his duties at that time.

Physical examination revealed tender, drumstick-like swelling of all toes. The toenails exhibited severe onycholysis with subungual debris (Figure 1A). Erythematous, hyperkeratotic plaque with hemorrhagic pustules was seen on the soles of both feet. In addition, the right sternoclavicular joint and both sacroiliac joints were tender and Mennell's sign was positive bilaterally.

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Figure 1. A, The patient's feet before treatment. All toes exhibit drumstick-like swelling and inflammation, and the toenails exhibit severe onycholysis with subungual debris. B, After treatment, swelling and inflammation of the toes resolved and toenails showed significant remodeling.

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Laboratory investigations showed an erythrocyte sedimentation rate of 16 mm/hour, a mildly elevated C-reactive protein level of 6.4 mg/liter, a gamma glutamyl transferase level of 30 units/liter, and an alkaline phosphatase level of 220 units/liter. HLA–B27 was positive. Rheumatoid factor, antinuclear antibodies, antineutrophil cytoplasmic antibodies, and results of serologic tests for the human immunodeficiency virus, hepatitis B and C, Chlamydia trachomatis, Treponema pallidum, and Yersinia enterocolitica were negative.

Results of a dermal biopsy from the plantar face of the right foot were consistent with psoriasis and revealed parakeratosis and neutrophils forming Munro's abscesses in the stratum corneum. In addition to psoriasiform hyperplasia of the epidermis, with club-shaped dermal papillae and exocytosis of lymphocytes into the slightly spongiotic epidermis, edematous dermal papillae with widely dilated capillary loops and perivascular lymphocytic infiltrate in the subpapillary dermis were seen.

Conventional radiographs of the forefeet revealed a periosteal reaction of the distal phalanx of both great toes. No erosions or cysts were detected. Three-phase bone scintigraphy showed increased uptake in both sacroiliac joints, the terminal phalanx of both great toes, and the right sternoclavicular joint in all phases. Fat-suppressed T2 magnetic resonance imaging (MRI) of the right foot demonstrated increased signal intensity and contrast enhancement of the first and third toes, the cuboid bone, and the proximal and medial phalanx of the fifth toe (Figure 2A). No articular process was seen.

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Figure 2. A, Fat-suppressed T2 magnetic resonance imaging (MRI) before treatment, showing contrast enhancement and a hyperintensive signal, which represents edema in the bone marrow in the first, third, and fifth toes. B, After treatment, MRI showed a normal intermediate signal of the bone marrow in the previously affected toes.

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Based on these findings, the patient was diagnosed as having POPP combined with an axial manifestation of psoriatic arthritis. Initial treatment with rofecoxib did not result in sufficient relief of pain, and subsequent immunosuppressive therapy with 15 mg of methotrexate once weekly was terminated after 4 weeks due to a significant increase in liver enzymes. Therefore, we decided to treat the patient with 40 mg of subcutaneous adalimumab every other week. Most interestingly, 10 days after the first injection of adalimumab, the patient experienced complete relief of pain and was able to return to work. Further treatment was well tolerated and no side effects were reported. After 4 months, a remarkable normalization of the toenails was achieved (Figure 1B) and the soles of both feet appeared to be nearly normal. In addition, MRI showed complete resolution of the initial inflammatory lesions (Figure 2B).

DISCUSSION

  1. Top of page
  2. Abstract
  3. CASE REPORT
  4. DISCUSSION
  5. REFERENCES

Based on the features psoriatic onychodystrophy and connective tissue thickening of the distal phalanx, including a periosteal reaction (1), the patient was diagnosed as having POPP. Of note, concomitant features characteristic of psoriatic arthritis as observed in our patient have also been described in other patients (5), and in 6 of the 15 cases reported so far, HLA–B27 was positive (1–12).

In addition to POPP, important differential diagnoses had to be considered in this patient. The absence of articular involvement of the distal interphalangeal joints allowed us to exclude the acral/digital type of psoriatic arthritis as a cause of the observed toe lesions. Synovitis, acne pustulosis, hyperostosis, and osteitis syndrome was taken into account because of the plantar pustular psoriatic lesions, but synovitis, folliculitis, and hyperostosis were not seen. Psoriatic nail dystrophy with fungal superinfection was excluded based on negative nail mycologic specimens.

In general, POPP is regarded as a unique variant of psoriatic arthritis, but its pathology and pathophysiology are not well understood. The association with HLA–B27 suggests similarities with other spondylarthropathies. McGonagle and colleagues (13) suggested a new concept in the pathogenesis of spondylarthropathies, in which inflammation originates at entheseal sites and is secondarily transmitted to other articular structures. If an analogous mechanism is operative in POPP, inflammation could spread from the subungual structures to the terminal phalanx through the fibrous area of the tendon–bone interface.

To our knowledge, treatment of POPP with a TNF-blocking agent has not previously been reported. Clinical studies demonstrate high efficacy of anti-TNF treatment in different subsets of spondylarthropathy (14–16). In addition to the effect on toenail remodeling after 4 months, the complete resolution of pain 10 days after initiation of adalimumab therapy is remarkable. We consider a TNF-blocking therapeutic strategy to be promising in this rare disease entity.

REFERENCES

  1. Top of page
  2. Abstract
  3. CASE REPORT
  4. DISCUSSION
  5. REFERENCES