We present the case of a 46-year-old man suffering from pain and dysesthesia over the ulnar nerve of his right arm for a duration of about 7 weeks. The presenting symptoms were tingling sensations in the lateral forearm and pain on palpation between the distal bicipital sulcus and the ulnar sulcus of the elbow. Electrodiagnostic examination showed a reduced nerve conduction velocity of 34.1 m/s over the affected cubital tunnel and 46 m/s distally in the forearm. The synopsis of the clinical signs leads to the patient’s referral to our department with the diagnosis of nerve compression syndrome of the ulnar nerve.
Clinical evaluation showed no muscle atrophy of the upper extremity but dysesthesia in the palmar area of the fourth and fifth fingers of his right hand. The pain over the ulnar nerve was triggered by palpation of the nerve between the distal bicipital sulcus and the ulnar sulcus of the elbow, where unexpectedly a subcutaneous tumor of 5×2 cm was palpable as a pathologic correlate. Magnetic resonance imaging (MRI) revealed a tumorous malformation of the ulnar nerve proximal to the ulnar groove matching the palpated size and most likely a schwannoma (Figure 1). This supported the indication for an exploration of the ulnar nerve due to the nerve compression, most likely caused by a peripheral nerve tumor.
Surgical exploration demonstrated the ulnar nerve distended over a length of 5 cm, indurated and entrapped into an inflammatory tissue (Figure 2). The perineurium was dissected and a sample of one fascicle of the ulnar nerve was obtained. Histopathology and immunohistochemistry with S100 and cytokeratin showed a localized and granulating inflammatory process in the perineurium and the ulnar nerve itself accompanied by substantial eosinophilia in the tissue (Figure 3). In summary, the patient’s ulnar nerve was compressed by a tumor of inflammatory origin, which was characterized by a substantial eosinophilia.
A literature search regarding inflammatory processes with an eosinophilic component was performed. Especially, histopathologic details directed the attention to eosinophilic fasciitis as a potential underlying disease. This rare systemic disease was reported in the first instance by Shulman in 1984 . He diagnosed a diffuse fasciitis resulting in sclerodermiformic skin indurations and joint contractures accompanied by hypergammaglobulinemia and the name-giving eosinophilia in the blood.
A comparison of our case to the current case series of eosinophilic fasciitis indicated that the here presented patient’s age is typical for the primary appearance of the disease , , . On the contrary, none of the described associated factors, such as arthropod-induced diseases (e.g. borreliosis), medication with statins or phenytoin, and severe disease of the thyroid or bone marrow (Table 1) , , were identified in our case. Laboratory diagnostics showed typical eosinophilia of the disease neither initially nor in the 6-month follow-up examination. Typical sclerodermiformic signs such as skin indurations or negative vein patterns  were not observed in any examination. Furthermore, there was no suggestion that the disease developed in its typical symmetric manifestation.
Factors associated with the development of eosinophilic fasciitis.
|Simvastatin||Myeloproliferative illnesses||Arthropod bites||Extreme physical exertion|
|Atorvastatin||Bone marrow transplantation||Borrelia infection|
Because our patient presented a particularly localized process, we decided to consult with the Clinic for Rheumatology of the University of Münster, Germany. Their evaluation as well as repeated blood examinations showed no further sign of a generalized disease and supported our diagnosis of a localized process. Therefore, the evaluation of treatment options showed the following findings.
In our case, the pathology of the nerve’s entrapment revealed the diagnosis of eosinophilic fasciitis. As eosinophilic fasciitis is an inflammatory and usually systemic disease, the general treatment consists of immunosuppression with common drugs, especially corticosteroids, in compliance with the actual literature . Any further surgical procedure such as tumor debulking or neurolysis was considered to be unrewarding in this special situation. Furthermore, in the author’s opinion, an additional surgical event would have the possible side effect of extensive scaring and could cause an even more severe entrapment of the nerve. However, in the patient’s good state of health with no systemic affection by the disease, there was currently no indication for a systemic therapy with corticosteroids. After a period of 4 weeks of intensive follow-ups combined with nonsteroidal anti-inflammatory drug (NSAID) treatment (diclofenac and later ibuprofen in reducing doses), the patient reported strongly attenuating neurologic symptoms over time.
In conclusion, the ulnar nerve of a 46-year-old male patient was entrapped by inflammatory tissue with substantial eosinophilia resulting in nerve compression syndrome. As eosinophilia and eosinophilic fasciitis known as Shulman’s disease are rare conditions, however, this might be a potential differential diagnosis for the underlying disease by first instance. Interestingly, there are reports in the literature that eosinophilic fasciitis occurs with isolated hand or forearm involvement and may cause carpal tunnel syndrome ,  and in one case even an ulnar neuropathy , ,  (Table 2). However, there is not yet a description of nerve compression syndrome with a localized entrapping of a peripheral nerve appearing as a peripheral nerve tumor like in our case. Altogether, this case proved the necessity to regard even rare diseases as a potential cause of an entrapment of peripheral nerves. This should lead surgeons to critical, differential diagnostic thinking and suggest that systemic diseases may be encountered during surgery due to their capability to mimic peripheral nerve tumors.
Differential diagnosis of eosinophilic fasciitis.
|Generalized eosinophilic fasciitis||Isolated version of eosinophilic fasciitis|
|Pseudoscleroderma||Carpal tunnel syndrome|
|Toxic oil syndrome|
Funding: Authors state no funding involved. Conflict of interest: Authors state no conflict of interest. Informed consent: Informed consent has been obtained from all individuals. Ethical approval: The research related to human use complies with all the relevant national regulations and institutional policies and was performed in accordance the tenets of the Helsinki Declaration.
Simon Thönnes: Design of the study; Data retrieval; Data analysis; Writing of the manuscript; Revision of the manuscript; Approval of the manuscript. Heiko Sorg: Design of the study; Data retrieval; Data analysis; Writing of the manuscript; Revision of the manuscript; Approval of the manuscript. Jörg Hauser: Design of the study; Revision of the manuscript; Approval of the manuscript; Analysis of literature. Daniel J. Tilkorn: Design of the study; Data retrieval; Writing of the manuscript; Revision of the manuscript; Approval of the manuscript; Data analysis; Analysis of literature.
Bischoff L, Derk CT. Eosinophilic fasciitis: demographics, disease pattern and response to treatment: report of 12 cases and review of the literature. Int J Dermatol 2008;47:29–35.
Berianu F, Cohen MD, Abril A, Ginsburg WW. Eosinophilic fasciitis: clinical characteristics and response to methotrexate. Int J Rheum Dis 2015;18:91–98.
Horacek E, Sator PG, Gschnait F. ‘Venous furrowing’: a clue to the diagnosis of eosinophilic fasciitis. A case of eosinophilic fasciitis ultimately treated with oral PUVA therapy. Dermatology 2007;215:89–90.
Fabri M, Hunzelmann N. Differential diagnosis of scleroderma and pseudoscleroderma. J Dtsch Dermatol Ges 2007;5:977–984.
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