key: cord-0900089-9x0530cb authors: Claudi, Carolin; Ganser, Joachim; Andreisek, Gustav; Vrugt, Bart title: A Juxta-Articular Myxoma of the Thumb A Case Report date: 2020-04-20 journal: Journal of hand surgery global online DOI: 10.1016/j.jhsg.2020.04.002 sha: 256e71fbec91690b85b212f52942406f4689c165 doc_id: 900089 cord_uid: 9x0530cb Abstract Juxta-articular myxomata are benign tumors which are mostly encountered in the vicinity of larger joints. Few cases in the hand have been reported. We present a case of a juxta-articular myxoma at the metacarpophalangeal joint of the thumb in a 40 year-old man. The preoperative diagnostic work-up included 4D MR-Angiography and ultrasound. The histochemical examination of the resected tumor established the diagnosis definitively. A follow-up MRI, scheduled without any clinical suspicion of tumor-recurrence, 9 months postoperatively, did not reveal any obvious recurrence. At 14 months, the patient has full motion without pain and declined any further imaging. Juxta-articular myxomata (JAM) are benign soft tissue neoplasms of mesenchymal origin. 18 These cystic tumors resemble a ganglion, and tend to recur after resection 1 thumb. Initially, this tumor was hardly noticeable, but it grew slowly over the past year. As it 27 was situated in the commissure between thumb and index finger, the pressure when 28 grasping larger objects provoked mild pain. 29 The clinical examination revealed a solid, circumscribed round mass of 25 mm which was 30 adherent to the ulnar-palmar aspect of the metacarpal joint of the thumb. It was scarcely 31 visible as the texture and color of the skin were normal. The tumor did not adhere to the 32 skin or tendons (figure 1). The stability and mobility of the thumb joints were not 33 compromised. 34 The clinical impression of close contact to the joint was verified by ultrasound. It was by MRI 35 (figure 2-4) and 4D MR-Angiography that the final diagnosis of a JAM was suspected. As a 36 well circumscribed, septated, scarcely vascularized (supported by duplex sonography) mass 37 without any pathological tumor-feeding vessels, it could be distinguished from a 38 myosarcoma. We forewent plain films as they seemed sufficiently replaced by MRI and 39 would only be useful to rule out any arthritic changes and bone infiltration. 40 Without suspicion of malignancy, we elected to proceed with marginal resection rather than 41 a biopsy to avoid a second operative procedure in a delicate region. 42 At surgery, the tumor could be completely resected without destruction of the joint 43 ligaments, tendons, vessels or nerves (figures 5, 6). 44 The histological examination revealed non-malignant spindle cells, embedded in a myxoid 45 matrix (figure 7). The diagnosis was confirmed immuno-histochemically with the affirmation 46 of CD34 and the exclusion of S100 and Actin. 47 The postoperative healing process was uneventful. The thumb regained full motion and 48 became completely pain free. 49 The regular follow-ups including ultrasound and MRI examination were initially scheduled on 50 a yearly basis. A first control-MRI, conducted without any clinical suspicion of tumor-51 recurrence postoperatively 9 months postoperatively, did not reveal any obvious recurrence. 52 At 14 months postoperatively, the patient is still pain and symptom free. Compared with the 53 contralateral side, he has full range of motion, equal power and normal sensibility in the 54 thumb. The patient elected to defer additional imaging during the COVID-19 pandemic. 55 Compliance with ethical standards 57 58 Conflict of interest: The authors declare that they have no conflict of interest. Although classified as benign lesions, myxomata can be locally destructive and thus cause 99 symptoms like pain or nerve palsy 15,17 . In the setting of local tissue destruction, one must 100 consider malignancy in the differential diagnosis 2 . 101 Macroscopically myxomata present as cystic formations 5 of soft or friable consistency, white 102 to yellow color, ranging from 2 to 6 cm in size 2 . Microscopically these tumors can appear 103 like fetal Wharton's jelly 18 . Few spindle-shaped fibroblast-type or stellate and fusiform cells 104 are found within reticulin fibers and a myxoid matrix. The mucin consists of hyaluronic acid 105 and mucopolysaccharides. Vasculature is usually poorly developed 1,3,19 . One report of an 106 unusually large myxoma in the hand even showed hormone receptors 20 . 107 A few differential diagnoses should be considered when seeing a patient with a swelling on 108 the hand or wrist like in our case. The most probable diagnosis would be a ganglion cyst 109 however these are smaller than JAM 5 , show no septation on MRI and have a less developed 110 myxoid component 8 . A hibernoma of the hand should also be considered, even as a rare 111 cause for carpal tunnel syndrome. This tumor of brown fat tissue shows spindle cells and 112 myxoid structures like a myxoma but would be positive for PS100 and CD 34 21 . 113 In cases of a rapidly growing mass, a sarcoma must always be considered 12,13 . Unfortunately 114 the diagnosis is often only confirmed by histologic examination after excision, so reoperation 115 may be needed 7 . Careful preoperative planning including MRI and even core biopsy should 116 be considered in these cases. Nodular fasciitis (NF) is a benign reactive myofibroblastic lesion 117 that may occur after trauma. It also presents as a rapidly growing subcutaneous mass and is 118 sometimes said to be a benign version of a sarcoma. Microscopically spindle-shaped cells in 119 myxoid matrix with collagen are found. NF is positive for alpha-smooth muscle actin, and 120 negative for many other markers (beta-catenin, S-100, CD 34, HMGA2, cytokeratin, EMA, 121 caldesmon, desmin) 22 . Lastly, an intramuscular myxoma should be considered in differential 122 diagnosis. It is more common in women around 50 and often affects large muscles in the 123 thigh or shoulder. In contrast to JAM it shows only minimal cystic changes and has a low 124 recurrence rate even with incomplete resection 1,2,8 . On CT, MRI and Ultrasound, they 125 present with an intrinsic high water content and a surrounding rim of fat 8 . Activating 126 missense mutations at the Arg201 codon of the Gs alpha gene leading to increased levels of 127 cyclic adenosine monophosphate are detected in intramuscular myxomata (and also found 128 in McCune-Albright Syndrome and sporadic fibrous dysplasia of bone), but not in JAM 16 . 129 In our case, the diagnosis of a JAM was confirmed after immuno-histochemical staining that 130 was positive for CD34 but negative for S100 and Actin. 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Myxoma of the palm Myxoma causing paralysis of the posterior 166 interosseous nerve Activating Gs alpha 169 mutation at Arg 201 codon does not occur in juxta-articular myxoma Posterior Interosseous nerve palsy caused by a 172 myxoma. The British Society for Surgery of the Hand Editorial: Myxoma of soft tissues Myxoma of the dorsal 176 hand Carpal tunnel syndrome due to hibernoma of the 178 wrist: Case report Intra-articular nodular fasciitis of the proximal 180 interphalangeal joint of a finger: A case report The authors do not have any conflicting interests concerning this article.