Localized eosinophilic fasciitis (Shulman's disease) as a differential diagnosis of nerve compression syndrome.

A 46-year-old man presented with clinical signs of nerve compression syndrome of his right ulnar nerve as confirmed by nerve conduction studies. Unexpectedly, clinical examination and magnetic resonance imaging (MRI) revealed a subcutaneous tumor of 5×2 cm above the ulnar groove. Surgical exploration and histopathology of biopsies demonstrated the nerve distended and entrapped into an eosinophilic, inflammatory tissue. This rare condition is consistent with localized eosinophilic fasciitis, with no systemic manifestations. There are reports of isolated forearm versions of the disease. However, none occurred with the entrapment of a peripheral nerve appearing as a peripheral nerve tumor, yet. Consequentially, the presented patient would not have benefitted from further surgical neurolysis or tumor debulking, as eosinophilic fasciitis is an inflammatory and systemic disease. The patient's symptoms decreased spontaneously after 4 weeks of postsurgical treatment, including nonsteroidal anti-inflammatory drugs (NSAIDs). Altogether, this case proved the necessity to regard even rare diseases as a potential cause of 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. ©2017 Thönnes S. et al., published by De Gruyter.

Case report

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.

Figure 1:

MRI of the right upper arm, axial section, TSE sequence.

Red arrow points to the distended right ulnar nerve, which shows significant signal enhancement.

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.

Figure 2:

Intraoperative situs during surgical exploration of the patient’s right ulnar nerve.

Incision of the right arm between the distal bicipital sulcus and the cubital tunnel. The ulnar nerve appears distended (gray arrow) and entrapped in inflammatory tissue (blue arrows).

Figure 3:

Histopathologic sections of the ulnar nerve (hematoxylin-and-eosin stain).

(A) Overview of a transversal section of the nerve fascicle. (B) Details of the inflammatory invasion of the nerve tissue accompanied by substantial eosinophilia (gray arrows mark representative eosinophilic granulocytes).

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 [1]. 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 [1], [2], [3]. 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) [2], [4], 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 [2] were not observed in any examination. Furthermore, there was no suggestion that the disease developed in its typical symmetric manifestation.

Table 1:

Factors associated with the development of eosinophilic fasciitis.

Medication	Severe diseases	Infections	Activity
Simvastatin	Myeloproliferative illnesses	Arthropod bites	Extreme physical exertion
Atorvastatin	Bone marrow transplantation	Borrelia infection
Lansoprazol	Hemodialysis
Phenytoin	Thyroid diseases

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 [3]. 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 [2], [3] and in one case even an ulnar neuropathy [2], [3], [5] (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.

Table 2:

Differential diagnosis of eosinophilic fasciitis.

Generalized eosinophilic fasciitis	Isolated version of eosinophilic fasciitis
Scleroderma	Tendonitis
Pseudoscleroderma	Carpal tunnel syndrome
Fibromyalgia
Toxic oil syndrome
Lyme disease

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