Letter: "Localised hypertrophic neuropathy" and hypertrophic polyneuropathy

Extraneural retiform perineuriomas. A report of four cases

We present here four cases of extraneural perineurioma (EP), which occurred in 31, 32, 42 and 43 year old women in the left hand, right arm (2 cases) and right axillary regions, respectively. All tumors were well circumscribed, with a thin capsule. They were 2, 2, 1.5 and 1.5 cm in the largest diameter. Microscopically all tumors had a distinctive appearance composed of interconnected cords of cells which ran in a parallel fashion or formed a characteristically looking cellular lattice. These cords were composed of cells with tapered to stellate shaped nuclei having one or two inconspicuous nucleoli. The space between the cells of the lattice was edematous and empty looking, or it was composed of myxoid matrix, or it was filled with characteristically looking globular deposits of collagen extracellular matrix. These globular deposits of collagen extracellular matrix often indented the nuclei, giving them a stellar appearance. Immunohistochemically all tumors reacted positively with antibodies to epithelial membrane antigen. Antibodies to smooth muscle actin, muscle-specific actin, S-100 protein, cytokeratin AE1/AE3, cytokeratin CAM 5.2, and HMB-45 gave uniformly negative immunohistochemical results.

Hypertrophic inflammatory neuropathy involving bilateral brachial plexus

BACKGROUND

The present case is an example of hypertrophic inflammatory neuropathy (HIN). This entity is a rare tumor-like, chronic inflammatory, focal or multifocal, mainly demyelinating neuropathy of unknown origin, most frequently involving the brachial plexus.

CASE DESCRIPTION

The authors describe a 67-year-old man presenting with a nodular mass in his right supraclavicular fossa. A nodular mass grossly resembling a schwannoma originating from a single nerve fascicle was surgically removed from the right C6 spinal nerve. Histologically, endoneurial edema, fibrosis, focal chronic inflammation, and extensive "onion bulb" formation were seen. Electron microscopy studies and immunohistochemistry proved that the onion bulb-forming cells were schwannian in nature and that the whorls of onion bulbs surrounded a generally demyelinated axon. Three months following surgery the patient developed acute painless paralysis of his right biceps brachii muscle that rapidly reversed; after that he remained neurologically asymptomatic. MRI revealed multiple fusiform mass lesions involving the brachial plexus bilaterally. Electrophysiologic studies demonstrated a bilateral, asymmetrical, mainly demyelinating neuropathy involving the brachial plexus; they failed to reveal any abnormality suggestive of generalized neuropathy.

CONCLUSION

HIN is different from other focal tumor-like neuropathies and in particular from localized hypertrophic neuropathy (LHN).

Focal neuropathy preceding chronic inflammatory demyelinating polyradiculoneuropathy by several years

We report three patients who exhibited an unusual clinical course of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) in which mononeuropathic limb weakness developed 2, 11 and 23 years, respectively, before the development of generalized polyradiculoneuropathy. The eventual diagnosis remained uncertain until other causes of neuropathy were excluded, and the clinical disorder progressed to involve the other limbs. Focal or regional variants of CIDP suggest that the pathologic, and perhaps the immunologic, abnormalities can be localized and selective for prolonged periods of time. Although this clinical variant seems to account for a small number of CIDP cases, its recognition may aid in making an early diagnosis.

Ultrastructural study of a perineurioma

A case of soft tissue tumor in the left brachialis muscle of a 49-year-old Japanese female patient was studied by electron microscopy. The tumor was diagnosed as intramuscular myxoma by light microscopy, but electron microscopic observation revealed that the tumor almost entirely consisted of cells similar to normal perineurial cells. The tumor cells possessed long, slender cytoplasmic processes covered by well-developed but discontinuous basal laminae, clusters of pinocytotic vesicles, and infrequent intercellular junctions. Perineurial cells have also been observed in other peripheral nerve lesions: neurofibromas, nerve sheath myxomas, and localized hypertrophic neuropathies. However, the term "perineurioma" or "perineurial cell tumor" should be reserved for discrete tumorous masses that are almost entirely composed of perineurial cells without evidence of residual axons, Schwann cells, fibroblasts, or tactile corpusclelike structures. Perineurioma may represent a third category of peripheral nerve sheath tumors, ultrastructurally distinct from schwannomas and neurofibromas.

Perineural cell tumor. Immunocytochemical and ultrastructural characterization. Relationship to other peripheral nerve tumors with a review of the literature

A perineurial cell tumor occurred in the shoulder girdle of a 47 year old woman. Light microscopy demonstrated a well-differentiated spindle-cell neoplasm of uncertain histogenesis. Immunocytochemical staining for S-100 protein was negative. Ultrastructural study revealed tumor cells with characteristics of perineurium, e.g. large numbers of micropinocytotic vesicles, numerous intercellular junctions, and elongated cell processes surrounded by basal lamina. Tumors of perineurial cells should be distinguished from the commonly recognized schwannomas as well as from various soft tissue lesions so that their biologic behavior can be better defined. A review of three other reported cases of perineurial cell tumors suggested that these tumors are benign and are usually located in the extremities and shoulder girdle. In addition, perineurial cell proliferation has been identified in other lesions of peripheral nerves, such as neurofibromas and localized hypertrophic neuropathy. Immunocytochemical and ultrastructural study of spindle-cell lesions with unusual histologic features may reveal that perineurial cell proliferation occurs more frequently than currently recognized.

Perineurioma as the cause of localized hypertrophic neuropathy

Clinical, electrodiagnostic, and morphological studies were performed on three patients with localized hypertrophic neuropathy (LHN). LHN is characterized clinically by slowly progressive motor mononeuropathy without significant pain or numbness. Nerve conduction studies and needle electrode examination show severe focal motor and sensory axonal loss. Morphological findings in the localized areas of enlarged nerves are different from those of generalized hypertrophic neuropathy, entrapment neuropathy, and neurofibroma, and consist of primary perineurial cell hyperplasia. The tumor is thus a perineurioma. This rare tumor can occur both in generalized neurofibromatosis and in isolated form and appears to be the cause of localized hypertrophic neuropathy.

Longitudinal sliding of the median nerve during movements of the upper limb

An incidental finding during recordings from the median nerve was that the nerve trunk slides longitudinally in its bed when the limb is moved. The amount of movement has been measured in 19 subjects. The observations are discussed with reference to the pathology of entrapment neuropathies and it is suggested that, where longitudinal movement of a peripheral nerve is restricted, continual trauma results from normal movements of the limb.

[Fusiform enlargement of mechanic origin of a peripheral nerve (author's transl)]

This paper reports on the study of a symptomless fusiform enlargement of the superficial peroneal nerve. The swelling was located in the part of the nerve passing through the aponevrosis. On incision of the epineurium small swellings were seen in the nerve fascicles. A fascicular biopsy was done and the fascicles studied by teasing and by optic and electron microscopy. Isolated nerve fiber study gave evidence of segmental demyelinisation with subsequent remyelinisation in almost all the myelinated fibers. These abnormalities were only encountered in the swollen part of the fascicle. A striking proliferation of cells was demonstrated in isolated fibers by counterstaining with hematoxylin. Electron microscopy showed primary demyelinsation and cellular proliferation affecting Schwann-cells (without onion bulb formations), fibroblasts and giant-vacuolated histiocytes. There was also a massive increase of endoneurial fluid. A few Bünger bands were seen. These rare abnormalities appear to be caused by chronic irritation of the nerve in its passage through the aponebrosis.