Focal myositis presenting with radial nerve palsy

Irreparable Radial Nerve Palsy Due to Delayed Diagnostic Management of a Giant Lipoma at the Proximal Forearm Resulting in a Triple Tendon Transfer Procedure: Case report and Brief Review of Literature

Background:

Non-traumatic radial nerve palsy (RNP) caused by local tumors is a rare and uncommon entity.

Methods:

A 62-year-old female presented with a left non-traumatic RNP, initially starting with weakness only. It was caused by a benign giant lipoma at the proximal forearm that was misdiagnosed over a period of 2 years. The slowly growth of the tumor led to an irreparable overstretching-related partial nerve disruption. For functional recovery of the patient, a triple tendon transfer procedure had to be performed.

Results:

Four months after surgery, the patient was completely able to perform her activities of daily living again. At the 10-months follow-up, strength of wrist extension, thumb's extension and abduction, and long fingers II-V extension had all improved to grade 4 in Medical Research Council scale (0-5). In order to restore motion, the patient reported that she would undergo the same triple tendon transfer procedure a second time where necessary. Due to the initially misdiagnosed tumor, there was an overall delayed duration of time for functional recovery of the patient.

Conclusion:

The triple tendon transfer procedure offers a useful and reliable method to restore functionality for patients sustaining irreparable RNP. However, it must be noted critically with our patient that this procedure probably would have been avoided. Initially, there was weakness only by entrapment of the radial nerve. RNP caused by local tumors are uncommon but known from the literature, and so it should be considered generally in differential diagnosis of non-traumatic RNP.

Compression and entrapment neuropathies

Peripheral nerve entrapments are frequent. They usually appear in anatomical tunnels such as the carpal tunnel. Nerve compressions may be due to external pressure such as the fibular nerve at the fibular head. Malignant or benign tumors may also damage the nerve. For each nerve from the upper and lower limbs, detailed clinical, electrophysiological, imaging, and therapeutic aspects are described. In the upper limbs, carpal tunnel syndrome and ulnar neuropathy at the elbow are the most frequent manifestations; the radial nerve is less frequently involved. Other nerves may occasionally be damaged and these are described also. In the lower limbs, the fibular nerve is most frequently involved, usually at the fibular head by external compression. Other nerves may also be involved and are therefore described. The clinical and electrophysiological examination are very important for the diagnosis, but imaging is also of great use. Treatments available for each nerve disease are discussed.

Focal myositis of the thigh misdiagnosed radiologically as rhabdomyosarcoma

Focal myositis is a commonly referenced, infrequently reported and poorly documented benign inflammatory pseudotumour, which may be misdiagnosed as a malignant tumour. We report the clinicopathologic features in a case of focal myositis in the thigh of a 15-year-old boy.

All-trans retinoic acid-induced focal myositis, synovitis, and mononeuritis

All-trans retinoic acid has revolutionized the treatment of acute promyelocytic leukemia, but this therapy is often complicated by the all-trans retinoic acid syndrome. Here we report a patient with newly diagnosed acute promyelocytic leukemia who developed acute focal myositis, synovitis, and possible vasculitis, after receiving all-trans retinoic acid therapy. We review the existing literature on this rare clinical entity, all-trans retinoic acid-induced myositis. This condition can manifest as fever, myalgia, arthralgia, and Sweet syndrome, accompanied by distinct magnetic resonance findings involving the lower extremity musculature. Treatment consists of discontinuation of the offending drug and often high dose corticosteroids.

Focal myositis: a clinicopathologic study of 115 cases of an intramuscular mass-like reactive process

BACKGROUND

Focal myositis is an uncommon inflammatory pseudotumor of skeletal muscle that can be confused with a variety of neoplastic and inflammatory diseases. It is often misunderstood because it presents as a tumor-like mass, but histologically resembles a skeletal muscle myopathy or dystrophy. We wanted to discuss the detailed morphologic and immunophenotypic features of the largest reported group of focal myositis patients.

DESIGN

Two hundred and six cases coded as "focal myositis" were culled from our files. Only 115 cases with adequate material, a solitary lesion, and correct diagnosis were included. A variety of immunohistochemical studies were performed, as were polymerase chain reaction for T cell receptor gene rearrangement and immunoglobulin heavy chain rearrangement.

RESULTS

Age ranged from 7 to 94 years (mean 41, median 36 y). Most patients were otherwise healthy, and with the exception of 10 cases, lacked antecedent trauma. Masses that ranged in size from 1.0 to 20.0 cm (median 3.0 cm, mean 3.9 cm) were reported in specific muscles of the lower extremities (including vastus lateralis, adductor muscle, and groin muscles, n=39; gastrocnemius, n=22), followed by the trunk, neck (mentalis, n=8; sternocleidomastoid muscle, n=8), and upper extremity. Histologically, these were solitary intramuscular processes composed of variable myopathic (93%) and focal neurogenic (89%) changes, fibrosis, and inflammation (97%), occasionally accompanied by prominent eosinophils (n=20). By immunohistochemistry, most cases had CD163-positive macrophages that were negative for S100 protein and CD1a. Lymphocytes were mostly CD3, CD4-positive lymphocytes that were negative for cytotoxic markers, TIA-1 and granzyme-B. Polymerase chain reaction did not show B cell or T cell rearrangement. In situ studies for Epstein-Barr-encoded receptor were negative, as was ALK-1 immunohistochemistry. Major histocompatibility complex-1 and weak IgG4 were focally positive in skeletal muscle. Cases with severe inflammation had increased numbers of CD20-positive B cells and CD123-positive plasmacytic dendritic cells. S100 was strongest in skeletal muscle fibers with vacuolar change. Clinical diagnostic considerations ranged from benign entities such as rhabdomyoma, intramuscular lipoma, fibromatosis, myositis ossificans, proliferative myositis, inflammatory myofibroblastic tumor, and inflammatory myopathy to malignant entities such as rhabdomyosarcoma, leiomyosarcoma, liposarcoma, and lymphoma. Available follow-up revealed spontaneous regression.

CONCLUSIONS

Focal myositis occurs in specific muscle groups of young adults of both sexes without significant trauma. It is a largely unrecognized entity with specific histology including myopathic, focal neurogenic, fibrosis, and inflammatory features. It can be easily mistaken for an inflammatory myopathy, dystrophy, alternate reactive, or even neoplastic process. Focal myositis seems to be a macrophage and T-cell-rich lesion that changes to B cell and dendritic plasmacytoid cells when markedly inflamed, but does not seem to have a known viral or molecular etiology. IgG4 presence may be linked to the fibrosis in these lesions; a possible transient autoimmune etiology cannot be excluded. Careful attention to reproducible clinicopathologic features can aid diagnosis and spare patients from excessive surgery or adverse therapy.

Heterotopic ossification of muscle and nerve: an unusual cause of painful mononeuropathy

We describe a case of painful radial mononeuropathy due to focal heterotopic ossification with diagnostic imaging, intraoperative illustration, and literature review.

Inflammatory pseudotumor of the peroneal nerve: case report and literature review

Inflammatory pseudotumors (IPTs) are a group of lesions of obscure etiology. Although they are presumably reactive, their exact pathogenesis is unknown. Inflammatory pseudotumors are identified in different organs; however, IPTs of the peripheral nerves have been rarely reported in the English literature. We report a 44-year-old woman who presented with left foot drop. Examination revealed a thickening in the posterolateral aspect of the popliteal fossa and features consistent with peroneal nerve palsy. Magnetic resonance imaging revealed a mass that may represent a Baker cyst or perineural sheath mass that was excised. After pathological examination, the case was diagnosed as IPT of peroneal nerve, and the patient received no further therapy. Inflammatory pseudotumors of the peripheral nerves, although rare, should always be of consideration in the differential diagnosis of peripheral nerve nodular mass lesions. They can mimic neoplastic nerve sheath lesions, clinically and radiologically. However, they are amenable to surgical cure with nerve-sparing surgery. Thus, despite their rarity, on dealing with neural S100 negative lesion, their inclusion is mandatory to avoid an unnecessary and a rather aggressive surgery.

Les malformations vasculaires à développement intramusculaire : un diagnostic différentiel rare de myosite focale

INTRODUCTION

Focal myositis constitutes an original and rare pathological entity, characterized by a localized inflammation within skeletal muscle, presenting as a soft tissue painful tumefaction. Diagnosis requires histological confirmation because of its non-specific clinical feature and the numerous differential diagnoses.

EXEGESIS

We report a 27 year-old man who presented with suggestive symptoms of focal myositis. MR imaging and echography were compatible with this diagnosis but also demonstrated the existence of a vascular component within the tumefaction. The diagnosis of a benign vascular malformation with intramuscular development was made by a surgically guided biopsy.

CONCLUSION

Vascular malformations are histologically heterogeneous with extremely variable clinical expressions. When they develop within skeletal muscle, they may mimic focal myositis. Hence, their diagnosis has to be evoked before performing muscle biopsy, because of the potential hemorrhagic risk.

Leg pain due to bilateral focal recurrent myositis in a hemodialysis patient

Leg pain is a common symptom in dialysis patients. In most cases, the cause is easily identified, but some rare causes have been recognized. We describe a case of focal myositis as the source of recurrent leg pain in a hemodialysis patient. This disease usually is self-limited and has a spontaneously favorable outcome. We review the differential diagnosis of leg pain in this patient population.

[Subacute proximal entrapment neuropathy of the radial nerve at the hiatus radialis]

Endogenous lesions of the radial nerve at the upper arm level and in the canalis spiralis are exceptional. Entrapment of the radial nerve in the hiatus radialis following forced arm movements, stretching, or as a consequence of pathologies of the surrounding tissue is known. We observed two patients suffering from a painful subacute middle radial nerve palsy with complete axonal degeneration caused by a lesion at the hiatus radialis, demonstrated by EMG, sonography, MRI, and surgical exploration. Successful nerve repair, in one case with a nerve graft, was performed. In both cases the most appropriate explanation was a focal neuritis with swelling of the nerve followed by strangulation at the hiatus radialis. In one case acute neuroborreliosis was the reason for the neuritis.

Focal myositis associated with S-1 radiculopathy: Report of two cases

Two cases are described of pseudotumoral calf hypertrophy after laminectomy for a compressive S-1 radiculopathy. The serum creatine kinase (CK) level was normal or mildly elevated. T2-weighted magnetic resonance imaging (MRI) showed calf enlargement, with an increased signal of the medial head of the gastrocnemius muscle. Electromyography revealed fibrillation potentials and positive sharp waves, but no complex repetitive discharges in the affected gastrocnemius muscle, with motor unit potentials having mixed neurogenic and myopathic features. Muscle biopsy revealed a focal myositis associated with some features of denervation. A brief course of corticosteroids was followed by remission clinically and improvement in the MRI findings.

Focal myopathy mimicking posterior interosseous nerve syndrome

A 25-year-old man developed weakness of extension of the right index, middle, and fourth fingers at the metacarpophalangeal joints, over 2 years. No sensory deficit was present. Nerve conduction studies, including the right radial nerve, were within normal limits. Needle electromyographic (EMG) examination showed myopathic changes that were limited to the right extensor digitorum communis and extensor indicis proprius muscles. An intravenous edrophonium chloride test had no effect on weakness and repetitive stimulation showed no significant decremental response. An EMG-guided open biopsy of the extensor digitorum communis muscle revealed severe myopathic changes. Evaluation for the cause of myopathic involvement was negative. After 13 months, clinical examination and electrophysiological studies showed no significant progression. This case exemplifies the fact that a focal myopathy may mimic an entrapment neuropathy.

Inflammatory pseudotumor of the median nerve. Case report and review of the literature

The authors report the presence of an inflammatory pseudotumor of the median nerve in a young woman who presented with a sensorimotor deficit in the median nerve area. Magnetic resonance (MR) images revealed a fusiform mass in the nerve, and the patient underwent surgery for a suspected peripheral nerve-sheath tumor. Her clinical condition improved slowly and notably. Histological study revealed a heterogeneous lymphoid infiltration with mononuclear cells, lymphocytes (mostly T cells), and plasmocytoid cells. Because of the unknown significance of this infiltration, the patient was examined to exclude the possible diagnosis of a systemic tumoral process. All the studies yielded negative results and no systemic disease was found. Later, control MR imaging revealed no tumoral remains, and electromyography demonstrated progressive improvement of median nerve function. The follow-up period has been 8 years. The cause of the lesion is unknown. The differential diagnosis includes benign and malignant peripheral nerve-sheath tumors, lymphoma, and all tumorlike lesions of peripheral nerves.