CASE REPORT. JA Dornbusch, DD Lewis,* MD Winter and MJ Dark CASE REPORT

Transcription

1 Atypical stenosing tenosynovitis of the abductor pollicis longus ascribed to proliferative fibrosis of the extensor retinaculum in a 10-year-old French Bulldog JA Dornbusch, DD Lewis,* MD Winter and MJ Dark A 10-year-old spayed female French Bulldog was presented with a 4-month history of progressive left thoracic limb lameness associated with the development of a firm mass located over the craniomedial aspect of the distal radius. The 3 3 cm mass was firm, sessile and located just proximal to the left antebrachiocarpal joint. Surgical debridement of the proliferative fibrous tissue, including partial excision of the extensor retinaculum, resolved the dog s lameness. Histopathological examination of the excised tissues revealed proliferative fibrosis engulfing the extensor retinaculum with mild inflammation and synovial hyperplasia. The dog remained sound on the limb for 10 months following surgery, despite progression of degenerative joint disease in the left carpus. KEYWORDS abductor pollicis longus; de Quervain s syndrome; dogs; extensor retinaculum; tenosynovitis We suspected an adult dog had an atypical presentation of stenotic tenosynovitis of the abductor pollicis longus, often referred to as de Quervain s tenosynovitis in humans. 1,2 A similar condition has been reported sporadically in dogs. 3 6 In humans, de Quervain s syndrome causes stenosing tenosynovitis of the first dorsal compartment of the carpus, which contains the abductor pollicis longus tendon and the extensor pollicis brevis tendon. 1,2 Although dogs do not have an extensor pollicis brevis tendon, the eponym de Quervain s syndrome has been used to describe stenosing tenosynovitis of the abductor pollicis longus tendon in dogs. 3 6 The presentation, treatment and outcome of this canine case are described. stenotic nares surgical correction and multiple congenital vertebral column anomalies. The owners had first noted a soft tissue mass, located just proximal to the left carpus, approximately 1 year prior to presentation. The mass had gradually increased in size. Arthrocentesis of the left carpus had been performed when the mass was first noted and cytology of the synovial fluid was normal. No further therapy was pursued at that time as the dog had no other clinical abnormalities associated with the mass. At 4 months prior to presentation the dog developed a consistent weight-bearing left thoracic limb lameness. As the lameness progressed, the dog became intermittently non-weight-bearing on the left thoracic limb. An intralesional injection of 6 mg triamcinolone was administered and the lameness resolved for 3 weeks. Unfortunately, the dog developed intolerable transient polyuria, so additional steroid administration was not considered when the lameness recurred. On examination, the dog had a nominal weight-bearing left thoracic limb lameness and the left carpus hyperextended slightly during weight-bearing. The dog had a body condition score of 5 (scale of 1 9), bilateral shoulder muscle atrophy and mild atrophy of the musculature of the left brachium. The left carpus could not be flexed beyond 90 o and attempts to flex the carpus further elicited a pain response. There was a 3 3 cm hemicircumferential, firm, sessile soft tissue mass located over the craniomedial aspect of the left antebrachium, just proximal to the carpus (Figure 1). Clinical features A 10-year-old spayed French Bulldog, weighing 6.7 kg, was referred to the University of Florida Small Animal Orthopedic Surgery Service with a history of progressive left thoracic limb lameness that was initially noted 4 months prior to presentation. The dog had a multitude of prior medical problems, including lameness ascribed to degenerative joint disease in the right scapulohumeral joint, pyometra treated by hysterectomy, pulmonic stenosis resolved with valvuloplasty, chronic polycythemia, intermittent chronic gastro-oesophgeal reflux, intermittent superficial pyoderma, *Corresponding author: University of Florida, College of Veterinary Medicine Gainesville, Florida, USA; LewisDa@ufl.edu FIGURE 1. A 10-year-old French Bulldog with a 3 4 month history of progressive left thoracic limb lameness. Note the 3 3 cm soft tissue mass associated with the craniomedial aspect of the left distal antebrachium. Australian Veterinary Practitioner 48 (1) March

2 Imaging Radiography of the left antebrachium and carpus showed an approximately 2.7 cm proximodistal 2.2 cm craniocaudal 1 cm mediolateral, well-defined soft tissue mass located just proximal to the dorsomedial aspect of the carpus. There was a moderate to marked, irregular, well-defined periosteal reaction along the craniomedial aspect of the distal radius, in the region of the groove for the abductor pollicis longus tendon. A well-defined, 4 mm mineralised fragment was present craniomedial to the antebrachiocarpal articulation. Osteophytes and enthesophytes were present in association with the proximal and distal margins of the accessory carpal bone, most pronounced at its articulation with the ulnar carpal bone. Additional osteophyte production was noted along the craniolateral aspect of the antebrachiocarpal joint and dorsomedial aspect of the middle carpal joint. Mild valgus deviation of the distal antebrachium and carpus was also noted, consistent with the dog s chondrodystrophic conformation (Figure 2). The distal forelimb was clipped and prepared for ultrasonographic examination of the soft tissue mass and associated musculoskeletal structures. Imaging was performed using a linear, 13-5 MHz transducer. A standoff pad was not used. Centred on the craniomedial aspect of the distal radius and encroaching on the dorsomedial aspect of the left carpus, a homogeneous soft tissue thickening, which extended craniolaterally, was noted superficial to the left abductor pollicis longus tendon. Deep to the medial portion of this thickening, the left abductor pollicis longus tendon was slightly compressed and thickened, measuring 1.8 mm wide compared with 1.1 mm for the right. The fibre pattern, however, FIGURE 2. Craniocaudal (A) and lateral (B) radiographs of the distal antebrachium show the circumferential soft tissue thickening, most pronounced craniomedially. Also note the irregular osteophytes along the craniodistomedial aspect of the radius (arrowheads), in the region of the distal radial groove. In addition, there are osteophytes associated with the antebrachiocarpal joint cranially and laterally. Findings are consistent with stenosing tenosynovitis of the abductor pollicus longus, as well as moderate antebrachiocarpal degenerative joint disease. was normal and linear, without evidence of disruption. There was irregular, periosteal new bone formation along the craniomedial margin of the distal radius, as well as the mineralised fragment noted radiographically (Figure 3). Based on the clinical imaging abnormalities, a tentative diagnosis of abductor pollicis longus tenosynovitis with associated left antebrachiocarpal and mild left middle carpal degenerative joint disease was made. The changes associated with the left accessory carpal bone suggested enthesopathy associated with the ligaments inserting on the accessory carpal bone. Treatment The dog was taken to surgery and the region of the left distal antebrachium and carpus was explored. A longitudinal incision was made over the cranial aspect of the distal left antebrachium, extending distally over the carpus. There was a markedly proliferative fibrotic hemicircumferential annular mass, which impinged the abductor pollicis longus tendon craniomedially, as well as the extensor tendons cranially (Figure 4). The proliferative mass, which included the annular extensor retinaculum, was excised. The underlying exposed abductor pollicis longus tendon sheath was hyperaemic, slightly thickened and oedematous, but otherwise intact. After debulking the proliferative fibrotic tissue, the abductor pollicis longus tendon and sheath, as well as the adjacent tissues, were no longer impinged. The tendon and associated sheath were not incised or debrided. The excised tissues were fixed in 10% neutral buffered formalin and processed routinely. The excised tissues consisted of dense proliferative fibrous tissue, which encased the extensor retinaculum with mild inflammation in areas adjacent to the synovium. Iron pigment (demonstrated via Prussian blue staining) was scattered throughout the sections (Figure 5). A soft padded bandage was applied to the distal left thoracic limb following surgery and the dog was administered methadone (0.1 mg/kg IV q4 6h) and cefazolin (22 mg/kg IV q6h). The day following surgery the dog was placing substantial weight on the affected limb with only a subtle lameness and the dog was discharged on a 10-day course of tramadol (3.7 mg/kg PO q8 12h). The bandage was removed 5 days after surgery and at the time the dog was sound on the left thoracic limb; 10 days after surgery, the dog was presented because of subcutaneous fluid accumulation at the surgical site. The dog was reluctant to place weight on the left thoracic limb when standing and there was turgid swelling of the surgical site. The incision was intact and healing and there was no drainage; 3 ml of translucent pink fluid was aspirated from the surgical site and cytological evaluation showed a poorly cellular fluid sample consistent with seroma formation without infection. A soft padded bandage was reapplied to the limb and maintained for another 3 weeks. The bandage was changed weekly. The dog remained comfortable and sound on the limb and the seroma did not recur. The dog was re-evaluated 10 months following surgery. The owners reported that the dog had been using the left thoracic limb without apparent lameness, but did report a gradual thickening of the left carpus, which was initially noted 4 months after surgery. The dog was consistently sound on the left thoracic limb without lameness, but the atrophy of the limb was unchanged. There was proliferation of the soft tissues surrounding the left carpus (5 cm mediolateral and 2 cm proximodistal). The proliferative tissue was palpably firm, with areas of mild fluctuance consistent with joint effusion. Range of motion of the carpus was had decreased slightly and the joint could no longer be flexed to 90 o. A mild pain response could be elicited when attempting to fully flex the carpus, but pain could not be elicited when direct pressure was applied to the distal left antebrachium or carpus. 6 Australian Veterinary Practitioner 48 (1) March 2018

3 FIGURE 3. Transverse (A) and longitudinal (B) ultrasound images of the tendon of the left abductor pollicis longus tendon showing the mild thickening of the tendon (arrowheads) with loss of the normal linear fibre pattern, marked heterogeneity, and a small volume of anechoic effusion. In addition, note the marked soft tissue thickening dorsal to the tendon. Lateral and proximal to the left of each image respectively. Repeat imaging Orthogonal view radiographs of the left carpus and distal antebrachium demonstrated severe osteophyte and enthesophyte formation that extended circumferentially around the distal aspect of the ulna, radius and proximal carpal bones. The soft tissue proliferation surrounding the carpus had increased in severity when compared with the radiographs obtained prior to surgery. Ultrasonographic examination of the left carpus and distal antebrachium was repeated and the images were compared with those obtained prior to the surgery. The previously noted thickening of the tissues overlying the distal aspect of the antebrachium and carpus was increased in severity and extended further medially, laterally and most notably distally. A large, irregular mineral fragment (5 mm), as well as numerous large osteophytes with periosteal reaction of the distomedial radius, surrounded the abductor pollicis longus tendon at this location. The tendon measured 1.5 mm in thickness (comparable to the pre-operative measurement), which remained thickened compared with the mm thick tendon in the unaffected, contralateral limb. The osseous changes noted were consistent with progressive, moderate antebrachiocarpal and middle carpal degenerative joint disease. A single drop of clear synovial fluid was obtained via arthrocentesis of the left carpus and examination of the fluid showed a low cellularity with mononuclear cells predominating and no overt cytological abnormalities. DISCUSSION The dog in the current report is presumed to have a variation of de Quervain s syndrome ascribed to extensive fibrosis of the distal antebrachial extensor retinaculum, which caused impingement of the abductor pollicis longus tendon and has not been described in previous reports. 3 6 FIGURE 4. Intraoperative image: Note the thickened fibrotic mass involving the extensor retinaculum. The mass courses from cranial to medial, and medially entraps the underlying abductor pollicis longus tendon and tendon sheath. FIGURE 5. Histopathological sections were fixed in 10% neutral buffered formalin, processed routinely and stained with haematoxylin and eosin. The extensor retinaculum is severely expanded by mature collagen fibres. There is no inflammation in this section. Bar = 200 µm. Australian Veterinary Practitioner 48 (1) March

4 The gradual onset of intermittent lameness associated with swelling that developed over the distal antebrachium was similar to abnormalities reported in dogs affected with de Quervain s syndrome. 3 6 Typically, the swelling in dogs with this syndrome has a distomedial proximocranial orientation following the course of the abductor pollicis longus tendon, secondary to thickening of the tendon and its sheath. 3 6 The swelling in the dog in the current report, however, had a hemicircumferential orientation that extended craniomedially over the distal radius, paralleling the radiocarpal articulation. Human patients with de Quervain s syndrome typically present with a gradual onset of pain and discomfort, the development of craniomedial swelling just proximal to the wrist and there is ultrasonographic evidence of stenosing tenosynovitis of the abductor pollicis longus and/or extensor pollicis brevis tendons. 1,2,7,8 The ultrasound abnormalities present in the dog in the current report were consistent with reported dogs affected with stenotic tenosynovitis of the abductor pollicis longus tendon. 3 5 Two ultrasonographic studies comparing human patients with de Quervain s syndrome and humans with normal wrists demonstrated consistently thicker extensor retinaculum in the humans with de Quervain s syndrome compared with the healthy control group; 7,8 however, pathological changes of the extensor retinaculum have not be described in previous reports of de Quervain s syndrome in dogs. 3 6 Treatment of the dog in the current report was based on a tentative working diagnosis of de Quervain s syndrome. 3 6 An intralesional steroid injection was initially administered and the dog s lameness transiently resolved. Possible repeated monthly steroid administration is often recommended in human patients if necessitated by a recurrence of clinical abnormalities. 1,2,9 11 Consideration was given to repeating the steroid injection when this dog s lameness recurred; however, the dog had become intolerably polydypsic and polyuric so the owners elected for surgical intervention. One study evaluating 94 human patients who underwent surgery to address de Quervain s syndrome reported that all patients had resolution of their pain and a full return of function in their affected hand. 12 Another study retrospectively evaluated patient satisfaction following surgical therapy of 43 human patients and reported a 91% cure rate. 13 Similar positive surgical results are reported in dogs undergoing surgery for de Quervain s syndrome. 3 6 Extensive fibrosis of the extensor retinaculum was identified intraoperatively and excision of this mass appeared to relieve impingement of the abductor pollicis longus tendon. The tendon sheath was mildly thickened and inflamed, but no further debridement was performed. Human patients who present with a diagnosis of de Quervain s tenosynovitis not infrequently have an accompanying thickened extensor retinaculum, 7,8,11 but this characteristic has not been previously described in dogs.3 6 Findings similar to those the radiocarpal articulation. Human patients with de Quervain s syndrome typically present with a gradual onset of pain and discomfort, the development of craniomedial swelling just proximal to the wrist and there is ultrasonographic evidence of stenosing tenosynovitis of the abductor pollicis longus and/or extensor pollicis brevis tendons. 1,2,7,8 The ultrasound abnormalities present in the dog in the current report were consistent with reported dogs affected with stenotic tenosynovitis of the abductor pollicis longus tendon. 3 5 Two ultrasonographic studies comparing human patients with de Quervain s syndrome and humans with normal wrists demonstrated consistently thicker extensor retinaculum in the humans with de Quervain s syndrome compared with the healthy control group; 7,8 however, pathological changes of the extensor retinaculum have not be described in previous reports of de Quervain s syndrome in dogs. 3 6 Treatment of the dog in the current report was based on a tentative working diagnosis of de Quervain s syndrome. 3 6 An intralesional steroid injection was initially administered and the dog s lameness transiently resolved. Possible repeated monthly steroid administration is often recommended in human patients if necessitated by a recurrence of clinical abnormalities. 1,2,9 11 Consideration was given to repeating the steroid injection when this dog s lameness recurred; however, the dog had become intolerably polydypsic and polyuric so the owners elected for surgical intervention. One study evaluating 94 human patients who underwent surgery to address de Quervain s syndrome reported that all patients had resolution of their pain and a full return of function in their affected hand. 12 Another study retrospectively evaluated patient satisfaction following surgical therapy of 43 human patients and reported a 91% cure rate. 13 Similar positive surgical results are reported in dogs undergoing surgery for de Quervain s syndrome. 3 6 Extensive fibrosis of the extensor retinaculum was identified intraoperatively and excision of this mass appeared to relieve impingement of the abductor pollicis longus tendon. The tendon sheath was mildly thickened and inflamed, but no further debridement was performed. Human patients who present with a diagnosis of de Quervain s tenosynovitis not infrequently have an accompanying thickened extensor retinaculum, 7,8,11 but this characteristic has not been previously described in dogs.3 6 Findings similar to those found in the dog in the current report, which included a severely proliferative extensor retinaculum with only mild abnormalities of the underlying tendon sheath, have been observed sporadically in human patients undergoing surgical treatment for de Quervain s tenosynovitis (Robert Matthias MD, Hand, Upper Extremity, and Microvascular Surgery, Dept of Orthopedics and Rehabilitation, University of Florida College of Medicine, August 2016, pers. comm.), but this phenomenon has not been reported in dogs. 3 6 Surgical excision of the extensor retinaculum overlying the first dorsal compartment, in conjunction with debridement of any proliferative tissues and excision of any intertendinous septa, is advocated in human patients who do not respond appropriately to medical management. 1,2,8 10,12 Partial excision of the extensor retinaculum resolved the lameness in the dog in this report and may represent an acceptable approach in other dogs affected with de Quervain s tenosynovitis. Evidence of myxoid degeneration, indicated by an accumulation of mucopolysaccharides, and chondroid metaplasia of the afflicted tendon and tendon sheath, are typical histopathological abnormalities in human patients affected with de Quervain s syndrome. 12,14 Similar histological abnormalities have been noted in some dogs with de Quervain s syndrome. 3,4,6 Histological examination of the submitted extensor retinaculum tissues from the dog in this report yielded evidence of mild chronic inflammation, as evidenced by iron with Prussian blue staining, adjacent to the synovial tissues. Mucicarmine, periodic acid-schiff and Alcian blue stains did not reveal evidence of myxoid degeneration in the tissue sections. CONCLUSION Although the dog in the current report had substantial progression of its degenerative joint disease in the left carpus, the specific lameness had not recurred 10 months after surgery. Although the exact cause of de Quervain s syndrome is not fully known, the pathophysiology behind the thickening of the extensor retinaculum secondary to frictional forces is well recognised in humans. 1,2,8 The dog in the current report had a chronic right thoracic limb lameness ascribed to degenerative joint disease of the right scapulohumeral joint, which may have contributed to the development of pathology in the distal left thoracic limb. Published reports of de Quervain s syndrome in dogs uniformly describe abnormalities of the abductor pollicis longus tendon or tendon sheath, 3 6 but we suspect that the 8 Australian Veterinary Practitioner 48 (1) March 2018

5 thickened extensor retinaculum was constricting the abductor pollicis longus tendon in the subjacent fibrosseous compartment of the distal radius, and was the primary source of the lameness in the dog reported here. The observed pathology may represent an atypical, or previously unrecognised variant, of de Quervain s tenosynovitis in dogs. 6. Moores AP, Comerford EJ. What is your diagnosis? J Small Anim Pract 2005;46: Volpe A, Pavoni M, Marchetta A et al. Ultrasound differentiation of two types of de Quervain s disease: the role of the retinaculum. Ann Rheum Dis 2010;69: CONFLICTS OF INTEREST AND SOURCES OF FUNDING No third-party funding or support was received in connection with the writing or publication of this manuscript. The authors declare no conflicts of interest. REFERENCES 1. Posner MS. Differential diagnosis of wrist pain: tendinitis, ganglia, and other syndromes. In: Peimer CA, editor. Surgery of the hand and upper extremity. 1st edn. McGraw-Hill Health Professions Division, New York, 1996; Wolfe SW. Tendinopathy. In: Wolfe SW, Hotchkiss RN, Pederson WC, et al., editors. Green s operative hand surgery. 6th edn. Elsevier Churchill Livingstone, Philadelphia, 2011; Grundmann S, Montavon PM. Stenosing tenosynovitis of the abductor pollicis longus muscle. Vet Comp Orthop Traumatol 2002;2001: Hittmair K, Groessl V, Mayrhofer E. Radiographic and ultrasonographic diagnosis of stenosing tenosynovitis of the abductor pollicis longus muscle in dogs. Vet Radiol Ultrasound 2012;53: Mayrhofer E, Putzenacher A, Fellner A et al. Tendovaginitis ossificans des Musculus abductor pollicis longus ( de Quervain ) als Lahmheitsursache bei einem Deutschen Schäferhund. Wien Tierarztl Monatsschr 2008;95: Lee KH, Kang CN, Lee BG et al. Ultrasonographic evaluation of the first extensor compartment of the wrist in de Quervain s disease. J Orthop Sci 2014;19: Anderson BC, Manthey R, Brouns MC. Treatment of de Quervain s tenosynovitis with corticosteroids: a prospective study of the response to local injection. Arthritis Rheumatol 1991;34: Altay MA, Erturk C, Isikan UE. De Quervain s disease treatment using partial resection of the extensor retinaculum: a short-term results survey. Orthop Traumatol Surg Res 2011;97: Capasso G, Testa V, Maffulli N et al. Surgical release of de Quervain s stenosing tenosynovitis postpartum: can it wait? Int Orthop 2002;26: Scheller A, Schuh R, Hönle W et al. Long-term results of surgical release of de Quervain s stenosing tenosynovitis. Int Orthop 2009;33: Ta KT, Eidelman D, Thomson JG. Patient satisfaction and outcomes of surgery for de Quervain s tenosynovitis. J Hand Surg Am 1999;24: Clarke MT, Lyall HA, Grant JW, Matthewson MH. The histopathology of de Quervain s disease. J Hand Surg Eur Vol 1998;23: Australian Veterinary Practitioner 48 (1) March