Soft tissue perineurioma: clinicopathologic analysis of 81 cases including those with atypical histologic features

Practical Application of Cytology and Core Biopsy in the Diagnosis of Mesenchymal Tumors

Soft tissue neoplasms are increasingly being sampled by core needle biopsy and fine-needle aspiration (FNA), and these small biopsy specimens pose unique diagnostic challenges. Many advances in ancillary testing enable detection of characteristic immunophenotypes and molecular alterations, allowing accurate classification of soft tissue tumors in these small biopsy samples. This review outlines pattern-based diagnostic approaches to core biopsies and FNAs of soft tissue neoplasms, including formulation of practical differential diagnoses and relevant application of ancillary tests.

Deep benign fibrous histiocytoma occurring in the kidney: Case report

RATIONALE

Deep benign fibrous histiocytoma (BFH) is relatively rare in contrast to superficial BFH involving the skin. Moreover, it was extremely rare for deep BFH occurring in the solid organ. To our knowledge, so far, only one case of deep BFH of the kidney was reported in English literature.

PATIENT CONCERNS

Herein, we report another case of deep BFH located in the kidney in a 88-year-old female. She was referred to our hospital for a severe pain in the right upper abdomen. Computed tomography revealed a round low-density shadow measuring 6 cm in the kidney.

DIAGNOSIS

The lesion was diagnosed as a deep BFH of the kidney, as the tumor was histologically predominately composed of bland ovoid cells arranged in a storiform pattern.

INTERVENTION

The patient underwent the total resection of the right kidney with the tumor in our hospital.

OUTCOMES

The postoperative course was uneventful. The patient was alive with no tumor recurrence or metastasis within 6 months of follow-up.

LESSONS

We present another case of deep BFH of the kidney. Because of the rarity, the tumor may be poorly recognized. The typical storiform pattern in histology may be helpful for diagnosis. This report serves to remind that deep BFH is also a differential diagnosis for a tumor with storiform pattern in the kidney.

Cutaneous Spindle Cell Neoplasms: Pattern-Based Diagnostic Approach

Context.—

Spindle cell neoplasms arising in the skin comprise a heterogeneous group of tumors with divergent lineages. Cutaneous spindle cell neoplasms are relatively common and present surgical pathologists with diagnostic challenges. Recognition of their histopathologies is important for correct diagnosis and management. The current review presents a pattern-based diagnostic approach to common cutaneous spindle cell neoplasms that often cause diagnostic difficulties.

Objective.—

To provide a useful guide for diagnosis of cutaneous spindle cell neoplasms.

Data Sources.—

PubMed (US National Library of Medicine) reports and the authors' personal experiences are reviewed.

Conclusions.—

The authors briefly summarize the histologic features and differential diagnoses of common cutaneous spindle cell neoplasms.

Perineurial-like Cells and EMA Expression in the Suprachoroidal Region of the Human Eye

The suprachoroidal region of the eye comprises vascular channels, melanocytes, and thin fibroblasts with elongated cytoplasm that are positioned directly adjacent to the densely collagenous sclera. Morphological similarities between these suprachoroidal fibroblasts and arachnoid cells and perineurial cells have been recognized, but whether these fibroblasts have a perineurial cell-like immunophenotype is not known. To further examine the relationship of these three cell types, we investigated the comparative expression of epithelial membrane antigen (EMA), the tight junction protein claudin-1, glucose transporter-1 (Glut-1), and CD34 in suprachoroidal fibroblasts, arachnoid of the optic nerve sheath, and perineurium of ciliary nerves in eight human eye specimens. Granular, diffuse, and cytoplasmic EMA expression was seen in suprachoroidal fibroblasts, but this was not contiguous with the similar pattern of EMA expression in adjacent perineurium and arachnoid. CD34 expression in suprachoroidal fibroblasts was also seen, similar to arachnoid and perineurium. Claudin-1 and Glut-1 were not consistently expressed in suprachoroidal fibroblasts, distinguishing them from perineurial cells in particular and suggesting that these fibroblasts do not arise directly from adjacent arachnoid or perineurium. Nonetheless, the overlapping morphology and protein expression suggest phenotypic similarities in these cells that protect and support adjacent retina, optic nerve, and peripheral nerve.

Recurrent multiple neurofibromatosis type 1 of the right lower limb

Neurofibromatosis type 1 is an autosomal dominant inherited disease, which is characterized by the presence of multiple neurofibromas. We encountered a case in which a sporadic dispersed neurofibroma recurred locally on numerous occasions extending over 16 years. The patient developed multiple masses with a focus of neurofibroma on the right lower limb, which were excised. The patient was initially diagnosed with inflammatory changes via computed tomography and magnetic resonance imaging; however, subsequently, pathological and immunohistochemical examinations revealed an intraneural neurofibroma. The patient underwent a comprehensive and complete local resection several times. After a continuous postoperative follow-up strategy, the patient recovered well. This report describes a case of primary manifestations of multiple and recurrent neurofibromas. We aim to emphasize the possibility of a unique, recurrent, non-healing neurofibroma and review the diagnostic techniques utilized to reach a definitive diagnosis. Early and complete surgical resection is an effective method to treat and prevent this type of neurofibroma.

Nonepithelial Tumors and Tumor-like Lesions of the Skin and Subcutis in Children

This overview of mesenchymal tumors presenting in the skin and/or subcutis in children brings together the range of neoplasms and hamartomas which are seen in this age-group. It is not surprising from the perspective of the pediatric or general surgical pathologist that vascular anomalies, including true neoplasms and vascular malformations, are the common phenotypic category. Since there is considerable morphologic overlap among these lesions, clinicopathologic correlation may be more important than for many of the other mesenchymal tumors. The skin and subcutis are the most common sites of clinical presentation for the infantile myofibroma which is the most common of fibrous mesenchymal tumors in children. Several of the other mesenchymal tumors are more common adults-like dermatofibrosarcoma protuberans, but nonetheless have an important presence in children, even as a congenital neoplasm. A lipomatous tumor in a young child should be considered as a possible manifestation of an overgrowth syndrome.

Melanocytic naevi with perineurial differentiation: a distinctive variant of neurotised naevi and a diagnostic pitfall with desmoplastic melanoma

AIMS

Spindle cell differentiation is not an uncommon finding in common acquired naevi, and may represent a form of neurotisation with Schwannian differentiation of melanocytes. Perineurial differentiation in this context appears to be very rare, and is only poorly documented in the literature. We therefore aimed to study this rare form of neurotisation in melanocytic naevi more comprehensively.

METHODS AND RESULTS

We have identified six melanocytic tumours showing spindle cell morphology and perineurial differentiation from routine and referral material. Clinical data and follow-up were obtained, and the histological and immunohistochemical features were analysed. The tumours affected middle-aged adults (median, 48 years; range, 26-74 years), with a wide anatomical distribution and benign follow-up (median, 13 months; range, 6-48 months). All tumours were nodular and circumscribed but asymmetrical, with extension into the deep dermis and superficial subcutis. A characteristic finding was a biphasic growth pattern with a lentiginous compound naevus in the superficial aspect and abrupt transition to a prominent nodular spindle cell proliferation in the deeper reaches. Spindle cells were bland and uniform, and arranged singly and in short fascicles in a loose fibromyxoid stroma. In areas, a whorled arrangement of slender spindle cells with wavy nuclei was seen. Distinctive intratumoral hypocellular nodules and peripheral lymphoid aggregates were additional features. By immunohistochemistry, the spindle cells were mainly S100-positive melanocytes. In areas, S100-negative/epithelial membrane antigen-positive spindle cells showing coexpression of Glut-1 and claudin-1 were closely admixed.

CONCLUSION

This perineurial differentiation probably represents a rare and unusual form of neurotisation. The tumours are benign but may be mistaken for desmoplastic melanoma. Awareness of and careful attention to the clinicopathological and immunohistochemical features allow reliable separation.

Case: Pediatric paratesticular soft tissue perineurinoma - A rare entity

Soft tissue perineuriomas are rare but benign tumours that are composed of peripheral nerve sheath and are most commonly located in the extremity. Diagnosis is confirmed by the immunohistochemical and ultrastructural features of the tumour. Paratesticular location is extremely rare; so far, only one case is reported. Herein, we report a second case of perineurioma in a 16-year-old male in the paratesticular region.

Repeated Multiple Neurofibromatosis Type 1 in the Right Lower Limb: A Case Report

Neurofibromatosis type 1 (NF1) is an autosomal-dominant genetic disease characterized by the presence of multiple neurofibromas. We encountered a unique case of NF1 that manifested as a recurrent soft tissue neurofibroma in the right lower limb that developed over a period of 16 years. The patient presented with a painless mass that was initially diagnosed as inflammatory changes via computed tomography and magnetic resonance imaging. However, the condition was subsequently diagnosed as an intraneural neurofibroma via pathological and immunohistochemical examination, which showed a focal to patchy lymphocytic chronic inflammatory infiltrate and several non-encapsulated masses with clear boundaries that were easily distinguishable from the adjacent neurofibroma. The mass relapsed three times over 3 years since it was discovered, for which the patient underwent comprehensive and complete local resection several times. Postoperative continuous follow-up confirmed that the patient recovered well. Early and complete surgical resection is an effective method for treating and preventing recurrent neurofibromas. However, because of the importance of pathologic examination in the diagnosis of such cases, this uncommon entity might be underreported in patients with NF1.

Soft Tissue Perineurioma in a Child With Neurofibromatosis Type 1: A Case Report and Review of the Literature

Soft tissue perineurioma is a rare benign peripheral nerve sheath tumor, especially in children. This manuscript presents an unusual case of soft tissue perineurioma in a 10-year-old boy with neurofibromatosis type 1. The patient presented with a lump in the region of the right breast. A subcutaneous, well circumscribed mass was removed. The cut surface was cream with a vaguely nodular appearance. Histology showed a spindle cell lesion with variable architecture and biphasic morphology. There was no nuclear atypia or pleomorphism. The differential diagnosis and other soft tissue lesions that can be seen in neurofibromatosis type 1 are discussed.

Cutaneous and Superficial Soft Tissue CD34+ Spindle Cell Proliferation

CONTEXT

- Cutaneous and superficial soft tissue spindle cell proliferations with CD34 expression represent a unique heterogeneous group of lesions. They can pose diagnostic challenges for unaware pathologists in their daily practice.

OBJECTIVE

- To review selected entities of CD34⁺ spindle cell proliferations in the skin and superficial soft tissue. The effective diagnostic approaches using clinical, histopathologic, and immunophenotypical findings are discussed within a broad spectrum of differential diagnosis.

DATA SOURCES

- All information used in the article is obtained from published literature by PubMed search and Internet-based search engines. The authors' collective experience and real-life examples are also used.

CONCLUSIONS

- Spindle cell proliferations with CD34 positivity can be worked up to a definitive diagnosis by using clinical, histopathologic, and immunophenotypical findings. Familiarity with these entities helps pathologists make the accurate diagnosis.

Low-grade fibromyxoid sarcoma of the external anal sphincter: a case report

BACKGROUND

Low-grade fibromyxoid sarcoma (LGFMS) is a rare soft tissue tumor that has a tendency to grow in the deep soft tissue of the trunk and extremities. Despite its benign appearance, the tumor has a high recurrence rate and metastatic potential. LGFMS in the perineal space is rare, and only a few cases have been reported. We present the first case of LGFMS to be located at the external anal sphincter.

CASE PRESENTATION

A 27-year-old male patient admitted to our Surgical Department with perianal pain and swollen for a year. The digital rectal examination revealed a perianal mass. Oral metronidazole and analgesia were prescribed on suspicion of perianal abscess failed to alleviate the symptom; hence, the patient was scheduled for surgery. Intraoperative diagnosis revealed an encapsulated tumor in the external anal sphincter that extended from the perianal region orally to the pararectal space. The results of immunohistochemistry (MUC4 staining) and FUS gene rearrangement by fluorescence in situ hybridization confirmed the diagnosis of LGFMS.

CONCLUSIONS

This case is unique in terms of the location of the rare soft tissue tumor. Although LGFMS is considered low grade, its unpredictable behavior necessitates a long-term follow-up.

Intranodal meningothelial proliferation in a patient with Cowden syndrome: a case report

Ectopic meningothelial proliferations are rare and can occur in a multitude of extracranial/spinal anatomic locations. Perineurioma is another uncommon entity that shares similar histological characteristics to those found in meningothelial proliferations. These include bland spindle cells with thin, bipolar nuclei; eosinophilic cytoplasm; and indistinct cell borders, arranged in short fascicles with whorl formation. Given their uncommon occurrence and shared histological and immunohistochemical features, their distinction can present a diagnostic challenge. Immunohistochemical studies can provide guidance when attempting to distinguish between these 2 lesions. Here, we present an unusual case of a patient with Cowden syndrome who was discovered to have a meningothelial proliferation within an axillary lymph node. To the best of our knowledge, this is the first case in which a meningothelial proliferation has been identified in a lymph node. Furthermore, the occurrence in a patient with Cowden syndrome is intriguing and raises the possibility of a pathogenetic link.

Extra-acral cutaneous sclerosing perineurioma with CD34 fingerprint pattern

Sclerosing perineuroma is a variant of extraneural perineurioma that, as a rule, occurs in acral sites. However, it has also been occasionally reported in non-acral regions. Recently, CD34 expression in a pattern reminiscent of the human fingerprint has been observed in a subset of perineuriomas, but this immunohistochemical finding has not been documented in non-acral sclerosing perineuriomas. We report a case of sclerosing perineurioma presenting CD34 expression in a fingerprint-like pattern on the skin of the neck (a previously unreported site for this neoplasm) of a 56-year-old man. In addition, alpha smooth-muscle actin showed a similar pattern of expression, suggesting that the cell population implicated in the remarkable immunolabeling is most probably fibroblastic/myofibroblastic. Other immunohistochemical findings included epithelial membrane antigen and claudin1-positive lesional cells, and the absence of S100, glucose transporter protein 1, MUC4 and desmin.

Pseudolipoblastic perineurioma: an unusual morphological variant of perineurioma that may simulate liposarcoma

Perineuriomas are rare peripheral nerve sheath tumors arising from or differentiating along the lines of normal perineurial cells. They can be divided into intraneural and soft tissue types, with the latter category including a significant number of morphological variants. Herein, we further expand their morphological spectrum to include "pseudolipoblastic" perineuriomas. These lesions occurred in the tongue of a 30-year-old man and in the triceps of a 67-year-old woman and were characterized by bland, epithelioid cells with striking intracytoplasmic vacuolization. The architecture varied, with some areas showing a striking "net-like" or "microreticular" pattern and smaller areas having a more typical spindled and whorled appearance. Clinical follow-up (5months and 52months, respectively) showed no evidence of local recurrence or metastasis. Multiple perineurial markers, including epithelial membrane antigen, claudin-1, GLUT-1, and collagen IV, were diffusely positive. Both cases were submitted in consultation out of concern that they represented high-grade liposarcomas. To the best of our knowledge, this unusual morphological variant of perineurioma has not been reported. These tumors appear to be entirely benign and should be cured with simple excision. Pseudolipoblastic perineuriomas should be distinguished from round cell and epithelioid pleomorphic liposarcomas, as well as from other tumors that may show prominent intracytoplasmic vacuolization.

Periprostatic Perineurioma, Description of a Case With Unusual Localization

Perineurioma is a rare entity, it is a benign peripheral nerve sheath tumor entirely composed of perineurial cells. A 62-year-old male patient was admitted to our hospital, suffering from scrotal and pelvic pain combined with a severe and continuous pain in his right thigh. A transrectal ultrasound revealed a periprostatic oval lesion of about 5 cm in maximum diameter. A sovrapubic laparotomy was performed with a complete tumor excision. The morphological and immunohistochemical data were most consistent with the diagnosis of perineurioma.

Perineurioma of scalp in an infant: A case report with short review of literature

Perineuriomas are rare benign peripheral nerve sheath tumor composed exclusively of perineurial cells. They have been classified into two main types according to their location – intraneural and extraneural (soft-tissue). Extraneural perineurioma are uncommon, found mostly in the soft tissue of the extremities and trunk, rare at other site. They mainly affect adults and have been sometimes described in children but are extremely rare in infants. We present a case of extraneural (soft-tissue) perineurioma of scalp in a 3-month-old infant, highlighting clinical, pathologic, and immunohistochemical features along with a discussion of the main differential diagnosis of this tumor. This is also the youngest case ever reported in the literature.

Peripheral Nerve Sheath Tumors

This article presents an overview of the diagnostic categories of benign and malignant nerve sheath tumors, including neuroma, neurofibroma, nerve sheath myxoma, perineurioma, schwannoma, and malignant peripheral nerve sheath tumor. The discussion emphasizes histologic patterns; ancillary studies, such as immunohistochemistry; and differential diagnoses. The information is of value to practicing pathologists in both community and academic settings.

Rapid Recurrence of a Benign Meningial Perineurioma

BACKGROUND

We describe a rare case of a rapidly recurring benign meningial-based perineurioma. Clinical, radiologic, and pathologic features of a rapidly recurring falxial perineurioma are described; the perineurioma was discovered incidentally in an 86-year-old woman.

CASE DESCRIPTION

Due to progressive gait disturbances and radiologically proven progression after a 3-year symptom-free interval, subtotal resection of a large falxial-based meningeal tumor was performed.

CONCLUSIONS

The pathologic examination confirmed the diagnosis of a perineurioma (World Health Organization grade I). Follow-up magnetic resonance tomography 5 months later due to neurologic deterioration revealed an abnormally rapidly growing and extensive local tumor recurrence. Due to the mass effect, reoperation was performed and adjuvant radiation of 20 Gy to the tumor bed was implemented thereafter. Meningeal-based perineuriomas of the central nervous system are extremely rare, and literature on proper management is scarce. Although histologic classification reveals a benign lesion, follow-up may be considered for this type of tumor.

UK guidance for the pathological reporting of serrated lesions of the colorectum

Bowel cancer screening programmes have highlighted to endoscopists and clinicians the spectrum of serrated colorectal lesions. One of the most significant developments has been the recognition that sessile serrated lesions (SSLs), while bearing histological resemblance to hyperplastic polyps (HPs), may be associated with the enhanced development of epithelial dysplasia and colorectal adenocarcinoma. Different minimum criteria exist for the diagnosis of SSLs and their differentiation from HPs. Furthermore, the spectrum of terminology used to describe the entire range of serrated lesions is wide. This variability has impaired interobserver agreement during their histopathological assessment. Here, we provide guidance for the histopathological reporting of serrated lesions, including a simplified nomenclature system. Essentially, we recommend use of the following terms: HP, SSL, SSL with dysplasia, traditional serrated adenoma (TSA) and mixed polyp. It is hoped that this standardisation of nomenclature will facilitate studies of the biological significance of serrated lesions in terms of the relative risk of disease progression.

[Nerve sheath tumours]

Peripheral nerve sheath tumors are common neoplasms in daily practice. Diagnosis and classification of most conventional peripheral nerve sheath tumors are relatively straightforward for the experienced observer; but on occasion, they are diagnostically challenging (especially with locally aggressive and malignant tumors). This article aims to provide an update of the data (clinical, histological, immunohistochemistry and genomic) of benign, intermediate and malignant peripheral nerve sheath tumors, thanks to the latest WHO "Classification of Tumors of Soft Tissue and Bone", published in 2013, which includes a new chapter on "Nerve Sheath Tumors". Advances in molecular biology have provided new insights into the nature of the various peripheral nerve sheath tumors, and have begun to suggest novel targeted therapeutic approaches.

Primary ectopic atypical meningioma in the renal hilum: a case report

BACKGROUND

Primary ectopic atypical meningioma involving the renal hilum is rare. This is, to our knowledge, only the second case report of a primary retroperitoneal meningioma and the first case of an atypical subtype in this location.

CASE PRESENTATION

A 53-year-old Han Chinese man presented with a 2-year history of left-side flank pain. An oval-shaped retroperitoneal mass was found in the left renal hilum on computed tomography, which was resected en bloc along with the kidney via laparotomy. According to the World Health Organization criteria, the tumor was histopathologically classified as a meningioma (Grade II, atypical). Five years later, the tumor recurred at the primary site with a similar histopathology. The patient received palliative resection, followed by radiotherapy (4500 cGy in 25 fractions). No relapse was found at 6-month follow-up.

CONCLUSION

We describe the clinical, radiographic and histopathological features of an unusual case of aggressive ectopic meningioma in the renal hilum. The patient presented with a massive retroperitoneal tumor without primary cerebral or secondary metastatic lesions; the preoperative diagnosis was naturally confined to the common retroperitoneal malignancies. This case is of interest to oncologists, because of both its rare location and aggressiveness; it not only enriched the spectrum of primary ectopic meningioma, but also reminded us of potential recurrence of an atypical meningioma. This case raises the issue of the etiology of such a rare tumor that needs further investigation, and more importantly demands long-term follow-up result.

Soft tissue perineurioma of the foot with 10q24 rearrangements: unique MRI features with histopathologic correlation

Perineurioma is an uncommon benign peripheral nerve sheath tumor with advanced perineurial differentiation. Two distinct subtypes are recognized: intraneural and soft tissue. We herein present a unique case of soft tissue perineurioma in the right foot of a 43-year-old man. Radiographs showed a non-specific soft tissue mass. On computed tomography scan, the mass was iso- to slightly hypodense relative to muscle. On T1- and T2-weighted images, the mass exhibited iso- to slightly low signal intensity relative to muscle with foci of high signal intensity. Slight contrast enhancement was noted on enhanced T1-weighted images with fat suppression. A marginal excision of the tumor was performed and histopathologic examination confirmed the diagnosis of soft tissue perineurioma. The clinicopathologic, radiologic, and cytogenetic findings are described, and the relevant literature is reviewed.

Reverse adipofascial flap after resection of a malignant perineurioma of the forearm

The authors describe a patient with recurrent perineurioma arising in the subcutaneous tissue of the dorsal forearm and extending along the forearm fascia. Soft tissue perineurioma is a rare, originally benign peripheral nerve sheath neoplasm arising from the perineurium, a protective cell barrier surrounding the individual fascicles in peripheral nerves. Perineurioma has only recently been recognized as an entity distinct from other nerve sheath tumors, such as schwannoma and neurofibroma, with unique morphologic, ultrastructural, and immunoreactive features. The recurrent tumor had converted into malignant perineurioma, defined as increased nuclear pleomorphism and cellularity. The ill-marginate feature extending along the fascia required wide resection, leaving a substantial defect on the distal forearm. Surgical repair of large forearm skin defects is challenging because of limited skin extensibility for flap creation, the prominence of the site in terms of aesthetic outcome, and the risk of damage to extrinsic muscles that control delicate hand movements. The reverse forearm adipofascial flap, which was based on distal perforators of the radial artery, was suitable for the current case to cover the exposed myotendinous junctions of the forearm extensor muscles. This flap did not sacrifice skin, a major vessel, or skeletal muscles, and preserved function at both the donor and the recipient sites. The texture of the graft was similar to that of the surrounding skin. The clinical and histopathologic features of this rare tumor are also described to aid in the differential diagnosis and as a reference for surgeons who treat soft tissue neoplasms and may encounter this type of soft tumor.

Myxoid perineurioma in a transplanted kidney

Perineuriomas are rare, benign peripheral nerve sheath tumors, most commonly found in the extremities and trunks. A handful of cases have been reported to arise from the retroperitoneum and in kidneys. To our knowledge, this is the first reported case of a myxoid perineurioma arising from a transplanted kidney. The patient is a 40-year-old Chinese male with end-stage kidney disease secondary to chronic sclerosing glomerulonephritis. He has a nonfunctioning renal graft in his right iliac fossa and a functioning graft in the left. Routine imaging found a mass in the nonfunctioning graft which was increasing in size. He underwent graft nephrectomy and histology revealed a myxoid perineurioma with no atypical features or malignancy.

Soft tissue perineurioma of the tongue: report of a case and review of the literature

Perineurioma is a rare benign tumor of the peripheral nervous system distinct from schwannomas and neurofibromas. It may be intraneural or extraneural (in the soft tissue). Extraneural soft tissue perineuriomas are uncommon; rare cases have been reported in the oral cavity. We present a case of soft tissue perineurioma in the tip of the tongue. The tumor was characterized by slender spindle cells, arranged in short fascicles or whorls, and focal areas showing a distinct storiform pattern. Tumor cells showed the immunohistochemical profile of perineurial cells, including epithelial membrane antigen. Smooth muscle actin, S-100, and CD34 were not expressed by the tumor cells. The tumor was surgically excised and in 2 years there has been no recurrence. Knowledge of the tumor in the oral cavity is important to reach a correct diagnosis and to avoid unnecessary aggressive local excision.

Tight junction protein claudin-1 is differentially expressed in craniopharyngioma subtypes and indicates invasive tumor growth

BACKGROUND

Claudins are tight junction proteins expressed in epithelial tissues that play important roles in cell polarity and adhesion. Altered distribution of claudin-1(CLDN1) affects cell mobility and tumor invasiveness. Craniopharyngiomas (CPs) represent epithelial tumors of the sellar region, consisting of adamantinomatous (adaCP) and papillary (papCP) variants. Their tendency to infiltrate surrounding brain structures complicates successful surgery. Reliable markers are required to predict tumor behavior and to establish individualized treatment protocols.

METHODS

We describe the distribution pattern of CLDN1 in a large cohort of 66 adaCPs, 21 papCPs, and 24 Rathke`s cleft cyst (RCC) cases using immunohistochemistry. CLDN1 mRNA levels were analyzed with qRT-PCR in 33 CP samples. The impact on the migration potential was studied in primary adaCP cell cultures (n = 11) treated with small interfering RNA (siRNA) for CLDN1. Furthermore, CLDN1 distribution patterns and expression levels were compared between invasive (n = 16) and noninvasive (n = 17) tumor groups.

RESULTS

PapCPs and RCCs exhibited a distinct homogenous and membranous expression pattern, whereas CLDN1 immunoreactivity appeared weaker and more heterogeneous in adaCPs. In the latter cases, whirl-like cell clusters showed complete absence of CLDN1. mRNA analysis confirmed reduced CLDN1 levels in adaCPs versus papCPs. Interestingly, invasive tumors exhibited significantly lower CLDN1 expression compared with noninvasive counterparts regardless of CP subtype. Accordingly, siRNA treatment for CLDN1 altered tumor cell migration in vitro.

CONCLUSION

CLDN1 represents a novel marker in the differential diagnosis of CP variants and RCCs. Low CLDN1 expression levels correlate with an invasive CP growth pattern and may serve as a prognostic marker.

Immunohistochemistry of soft tissue tumours - review with emphasis on 10 markers

Immunohistochemistry is an integral component in the proper analysis of soft tissue tumours, and a simple panel of six markers is useful in practical triage: CD34, desmin, epithelial membrane antigen (EMA), keratin cocktail AE1/AE3, S100 protein and alpha smooth muscle actin (SMA). These markers frequently assist in the differential diagnosis of fibroblastic, myoid, nerve sheath and perineurial cell tumours, synovial and epithelioid sarcoma and others. However, they all are multispecific, so that one has to be cognizant of their distribution in normal and neoplastic tissues. Four additional useful markers for specific tumour types are discussed here: CD31 and ERG for vascular endothelial tumours, and KIT and DOG1/Ano-1 for gastrointestinal stromal tumours (GISTs). However, hardly any marker is totally monospecific for any one type of tumour. Furthermore, variably lineage-specific markers do not usually distinguish between benign and malignant proliferations, so that this distinction has to be made on histological grounds. Immunohistochemical evaluation is most useful, efficient and cost-effective when used in the context of careful histological evaluation by an experienced pathologist, aware of all diagnostic entities and their histological spectra. Additional diagnostic steps that must be considered in difficult cases include clinicoradiological correlation and additional sampling of remaining wet tissue, if possible.

Mesenchymal Tumors of the Gastrointestinal Tract Other than GIST

Mesenchymal tumors involve the gastrointestinal (GI) tract more frequently than other visceral organs. Many such tumors are small, and are benign and increasingly being detected incidentally during colonoscopic screening. Some tumors show distinctive features at this site, such as schwannoma and clear cell sarcoma-like tumor of the GI tract. Without knowledge of these features, recognition of these tumor types can be difficult. This reviews addresses recent developments and diagnostic features of mesenchymal tumors of the GI tract other than gastrointestinal stromal tumor (GIST).