Perineurial cell tumor (perineurioma) with granular cells

A Rare Perineurioma/Granular Cell Tumor Hybrid Peripheral Nerve Sheath Tumor

Hybrid peripheral nerve sheath tumors (PNSTs) are rare benign composite neoplasms demonstrating features of multiple endogenous nerve sheath cell types. Hybrid PNSTs with granular cell components are exceedingly rare. Only a handful number of hybrid PNSTs composed of granular cell tumor and perineurioma have been described to date. We present a rare hybrid of perineurioma and granular cell tumor and review the literature.

Congenital cutaneous non-neural granular cell tumor mimicking herpetic infection: Case report and review of the literature

We present a case of a female neonate with a cluster of six skin colored to yellowish pseudovesicular papules on her right forearm present since birth, initially thought to be a herpes simplex virus infection. Punch biopsy with immunostaining revealed a diagnosis of S100-negative, CD163-positive congenital cutaneous non-neural granular cell tumor. Only four other reports are presented in the literature of this entity, three of which also presented on the arm with somewhat similar clinical findings. We briefly reviewed the subtypes of classic and S100-negative non-neural granular cell tumors.

Intraneural granular cell tumor: Histologic spectrum and histogenetic implication

Granular cell tumor (GCT), despite its putative neural origin, commonly occurs in extraneural sites; only six single case reports of intraneural GCT have been described. We report an unique case as the only one with motor dysfunction, the longest duration of symptoms, and largest tumor size with resultant muscle atrophy and fatty infiltration. Upon review of these cases, the striking feature of intraneural GCT lies in its histologic variety, ranging from benign GCT, through plexiform, hybrid GCT and perineurioma to malignant GCT, encompassing the full spectrum of extraneural GCT. As the immunophenotypes of schwannoma and GCT are not exactly identical, together with evidence from ultrastructural studies, the more reasonable and likely possibility is that GCT originates from undifferentiated mesenchymal cells acquiring partial schwannian differentiation. Such postulation by virtue of the widespread occurrence of mesenchymal cells in the soft tissue, better explains the topographic distribution of GCT in extraneural and intraneural location.

Extraneural sclerosing perineurioma of the buccal mucosa: a case report and clinicopathologic review

The perineurioma is an infrequently encountered benign peripheral nerve sheath tumor composed of a clonal proliferation of perineurial cells. Rare cases of perineurioma have been reported in the oral cavity. An extraneural sclerosing perineurioma arising in the buccal mucosa of a 17-year-old male is presented. Histopathologically, the tumor is composed of a well circumscribed nodular proliferation of spindle cells arranged in a storiform growth pattern, in some areas subtly arranged around vascular channels. The tumor cells reveal positive immunostaining for epithelial membrane antigen (EMA), collagen type IV and vimentin, and negative immunostaining for S-100 protein, consistent with a perineurial origin. To the best of our knowledge, this case represents the first report of an extraneural sclerosing perineurioma involving the oral cavity.

An infiltrative variant of non-neural granular cell tumor: a case report

Dermal non-neural granular cell tumors are rare tumors of indeterminate lineage that typically present as well-circumscribed tumors with nuclear pleomorphism and mitotic activity. We describe a dermal non-neural granular cell tumor with a distinctive growth pattern with granular cells interspersed between collagen bundles. This asymptomatic papule arose on the scapula of a 46-year-old woman and consisted of a mixture of epithelioid and spindled granular cells. The immunohistochemical characteristics were similar to those of previously reported dermal non-neural granular cell tumors. Despite mild nuclear pleomorphism and dispersion of lesional cells among collagen bundles, mitoses were not present and Ki-67 staining indicated a low proliferative rate. In addition to being S-100 protein negative and NKI/C3 positive, our case was positive for PGP9.5 and weakly positive for neuron-specific enolase, a staining pattern similar to what has been observed for cellular neurothekeomas. Our case could represent a dermal non-neural granular cell tumor with unique architecture, a granular cellular neurothekeoma or a granular cell dermatofibroma. As both dermal non-neural granular cell tumor and cellular neurothekeoma are of indeterminate lineage, our case with features characteristic of both entities may suggest a common precursor or lineage for dermal non-neural granular cell tumor and cellular neurothekeoma.

Multiple hybrid granular cell tumor-perineuriomas

Hybrid peripheral nerve sheath tumors (PNSTs) are recently recognized, rarely reported entities. Very few hybrid PNSTs with elements of perineurioma have been reported. We report a case of a 47-year-old man who presented with multiple (>20) cutaneous nodules on all 4 extremities, present since childhood. The patient and his family had no history of other PNSTs, other neural-origin tumors, or genetic disorders, including neurofibromatosis. Five excised lesions are well circumscribed but unencapsulated nodular tumors composed of cytologically bland spindled cells with tapering nuclei and indistinct cytoplasm arranged in a storiform pattern in a collagenous matrix. Scattered among these cells are large granular eosinophilic cells. The spindled cells are epithelial membrane antigen-positive and S-100 protein negative. The cytoplasm of the granular cells contains abundant S-100 protein, NK1/C3, and CD68-positive granules. Sparse nerve fascicles contain neurofilament-positive axons. Each tumor also contains poorly marginated areas that histologically resemble pure granular cell tumor, and superficial biopsies of these tumors can histologically resemble pure granular cell tumors. Considering a Schwannian origin for both perineurial and granular cells can provide a logical explanation for the pathogenesis of this case. To the best of our knowledge, our case is the first report of multiple hybrid granular cell tumor-perineurioma.

The normal and neoplastic perineurium: a review

Peripheral nerves consist of 3 layers with differing characteristics: the endoneurium, perineurium, and epineurium. The perineurium represents a continuum with the pia-arachnoid from the central nervous system and extends distally with the sheath of capsular cells of peripheral sensorial organs and propioceptive receptors. It is made of layers of flattened cells surrounded by a basement membrane and collagen fibers, forming concentrically laminated structures around single nerve fascicles. Functionally, the perineurium modulates external stretching forces (that could be potentially harmful for nerve fibers), and along with endoneurial vessels, forms the blood-nerve barrier. Multiple pathologic conditions associated with the perineurium have been described. Perineurial invasion is considered an important prognostic factor in several malignant neoplasms. Perineuriomas are true benign infrequent perineurial cell neoplasms that have been divided in 2 categories: those with intraneural localization and a more common extraneural (soft tissue) group, including sclerosing and reticular variants. Sporadic cases of malignant perineuromas have been reported. Interestingly, neurofibromas and malignant peripheral nerve sheath tumors may also display perineurial cell differentiation. The histologic appearance of perineuriomas may overlap with other soft tissue spindle cell neoplasms. Immunohistochemistry is imperative for the diagnosis, although in certain cases ultrastructural studies may be needed. Typical perineuriomas are positive for epithelial membrane antigen, glucose transporter-1-1, and claudin-1, and negative for S-100 protein and neurofilaments. Perineuriomas have mostly simple karyotypes, with one or few chromosomal rearrangements or numerical changes and it seems that specific cytogenetic aberrations may correlate with perineurioma subtype.

Perineurioma: a distinctive and underrecognized peripheral nerve sheath neoplasm

CONTEXT

Perineuriomas are benign peripheral nerve sheath neoplasms composed of perineurial cells with characteristic immunohistochemical and ultrastructural features. They have been traditionally classified into two main types according to their location--intraneural and extraneural--and overlap histologically with many other tumors, which may be diagnostically challenging to general surgical pathologists.

OBJECTIVE

To review the clinical, morphologic, immunohistochemical, ultrastructural, cytogenetic, and molecular genetic aspects of perineurioma, as well as to discuss its clinicopathologic variants and differential diagnosis.

DATA SOURCES

English-language literature published between 1966 and 2005 was reviewed.

CONCLUSIONS

The correct identification of perineuriomas is important to avoid unnecessary overtreatment. The histologic diagnosis should be confirmed through immunohistochemical studies (including epithelial membrane antigen, S100 protein, and more recently described antibodies such as claudin-1 and GLUT1) or electron microscopy. Cytogenetic and molecular genetic studies are still of limited value for the diagnosis of perineuriomas but may play a fundamental role in excluding important differential diagnoses and also in helping elucidate the biology of these poorly known neoplasms.

Reticular and plexiform perineurioma: clinicopathological and immunohistochemical analysis of two cases and review of perineurial neoplasms of skin and soft tissues

Perineurioma represents a recently described and relatively rare neoplasm in the spectrum of benign peripheral nerve sheath tumours composed of perineurial cells staining immunohistochemically positive for epithelial membrane antigen (EMA). In addition to intraneural, extraneural and sclerosing perineurioma, rare variants of perineurioma may occur, and their knowledge is important in the differential diagnosis of mesenchymal tumours of different lines of differentiation and clinically more aggressive neoplasms. We present a case of deep-seated reticular perineurioma arising on the upper arm of a 34-year-old female and a case of a dermal plexiform perineurioma arising on the lower lip of a 60-year-old female. The diagnosis was confirmed in both cases immunohistochemically; neoplastic cells stained positively for EMA and for the newly described perineurial markers, claudin-1 and glut-1. The morphological spectrum and the differential diagnosis of perineurial neoplasms of skin and soft tissues are discussed.

Extraneural perineurioma of the face: an unusual cutaneous presentation of an uncommon tumour

Perineurioma is an uncommon, benign tumour of the peripheral nerve sheath that has two major clinicopathological forms -- intraneural and extraneural. We present a case of extraneural perineurioma that occurred at an unusual site -- the facial skin of a 70-year-old woman -- which illustrates the wide, and potentially misleading, clinicopathological spectrum of this poorly recognized tumour.

The S100 family of multipurpose calcium-binding proteins

Antibodies reactive with S100 protein are useful markers in a diagnostic immunohistochemistry laboratory dealing with cutaneous tumors. However, S100 protein is not a single protein but instead a group of S100 proteins with diverse functions. S100 proteins constitute a family of acidic calcium-binding proteins that are important in intracellular calcium metabolism. Recent evidence that some S100 proteins are secreted makes it likely that they are also involved in cell-cell interactions. The exploration of the status of the different members of the S100 family may yield not only diagnostic clues but also relevant functional information about the cells. Considerable recent progress has been made in our understanding of S100 proteins. This review surveys some of these findings that may be either directly or indirectly relevant to cutaneous pathology.