Dermal nerve sheath myxoma: a study of three cases

A YAP1::TFE3 cutaneous low-grade fibromyxoid neoplasm: A novel entity!

Cutaneous fibromyxoid neoplasms (CFMN) comprise a vast category of benign and malignant tumors that include, but are not limited to, low-grade fibromyxoid sarcoma, myxofibrosarcoma, myxoid dermatofibrosarcoma protuberans, myxoid solitary fibrous tumor, and myxoid neurofibroma with differing implications for treatment and prognosis. Herein, a case of CFMN arising as a painless, slow-growing, flesh-colored forearm mass in a 53-year-old female is presented. The neoplasm comprised of copious myxoid material with banal spindle cells, exhibiting mild hyperchromasia, dissecting the dermal collagen table. Focal perivascular accentuation of spindle cells was identified in the absence of vasoformative features. Immunohistochemically, lesional cells were strongly and diffusely positive for CD34 and multifocally for Factor XIIIa and epithelial membrane antigen while negative for CD31, ERG, FLI-1, D2-40, smooth muscle actin, Desmin, S100, HMB-45, STAT6, MUC4, and keratins. RNA- and DNA-sequencing identified a YAP1::TFE3 fusion transcript that were subsequently corroborated by fluorescence in situ hybridization and immunohistochemistry for TFE3 (Xp11.23) locus rearrangement and strong, diffuse TFE3 immunoreactivity, respectively. To date, the YAP1::TFE3 fusion has only been identified in a subset of epithelioid hemangioendotheliomas and clear cell stromal tumors of the lung. This is the first report of a CFMN featuring a YAP1::TFE3 fusion (YAP1 Exon 1 and TFE3 Exon 4). The morphologic findings are unlike those previously described for epithelioid hemangioendothelioma and suggest that this neoplasm may represent a yet unclassified or novel CFMN entity. Although the patient is 1-year status postsurgical excision with no evidence of clinical recurrence, the clinical behavior of this novel entity remains to be fully characterized.

Neurogenic tumors of soft tissue

Neurogenic tumors are an uncommon yet important category of soft tissue tumors in children and adolescents because of their frequent association with various genetic syndromes. The heterogeneous cellular composition of the peripheral nerve and the wide metaplastic capacity of the neural crest and its derivatives generate a variety of neoplasms with neurogenic differentiation. This article reviews the clinicopathologic features and differential diagnosis of neurogenic tumors in the first two decades of life, and highlights use of selected ancillary methods for diagnosis.

A rare case of atypical cellular neurothekeoma in a 68-year-old woman

Cellular neurothekeoma is a benign dermal lesion of uncertain differentiation. The atypical variant of cellular neurothekeoma, characterized by features such as large size, deep penetration, diffusely infiltrative borders, vascular invasion, high mitotic rate and marked cytologic pleomorphism, has been very rarely reported in the literature. We present the clinical, histopathological and immunohistochemical profile of a new case of atypical cellular neurothekeoma in a 68-year-old female patient who was diagnosed with ductal breast carcinoma in situ before. An erythematous painless papule arose in her right breast, and tentative clinical diagnosis was orientated toward skin metastasis of breast cancer or fibroma. Upon histological examination, the lesion showed the histological and immunohistochemical features of atypical variant of cellular neurothekeoma with high mitotic rate, marked cellular pleomorphism and penetration into subcutaneous fat. A further unusual feature in our patient was her age, because she is the oldest patient reported in the literature with diagnosis of atypical cellular neurothekeoma so far. Prognosis remains uncertain because only few cases of atypical cellular neurothekeoma have been reported in the literature, with a very limited follow-up time. Our report contributes to a better characterization of the clinical and morphologic features of atypical cellular neurothekeoma.

Atypical cellular neurothekeoma--a diagnosis to be aware of

We present a rare case of atypical cellular neurothekeoma arising in the area of a previous nose piercing on the ala of a 34-year-old female. Neurothekeoma is a benign tumour of probable nerve sheath origin. The cell of origin for neurothekeoma is still unknown but most ultrastructural and immunohistochemical studies have favoured the Schwann cell perineurium or fibroblasts. A similar but distinct, more cellular variant with a less prominent myxoid component, was termed cellular neurothekeoma and, unlike myxoid neurothekeoma, the cellular variety generally lacks immunoreactivity to most neuronal markers. Atypical cellular neurothekeoma is characterised by the following features: large size of up to 6 cm, penetration into subcutaneous fat and or muscle, diffusely infiltrating borders, vascular invasion, a high mitotic rate and marked cytological pleomorphism. In this report we provide a review of the relevant literature and describe the clinical, histological and immunohistochemical features of an atypical cellular neurothekeoma excised from the ala nasi of a 34-year-old female, a hitherto unreported lesion in the plastic surgery literature.

Cellular Neurothekeoma: Detailed Characterization in a Series of 133 Cases

Cellular neurothekeomas are distinctive benign cutaneous tumors of uncertain histogenesis. As relatively few cases have been reported, their clinical features and morphologic spectrum remain incompletely defined, and the significance of atypical histologic features is uncertain. This study examined the clinicopathologic and immunohistochemical features of 133 cellular neurothekeomas received between 1987 and 2003. There was a 1.8:1 female predominance, with a mean age of 25 years (84% <40 y). Mean tumor size was 1.1 cm (range: 0.3 to 6 cm; 90% <2 cm). The tumors arose most often on the upper limb (35%) or head and neck (33%). Fifty-two percent of the tumors were limited to the dermis, and 48% also involved superficial subcutaneous tissue. In 30% of cases, neurothekeoma was suggested by the referring pathologist; the most common other diagnoses offered were plexiform fibrohistiocytic tumor, benign fibrous histiocytoma, and a low-grade sarcoma. Histologically, most cases were poorly marginated; 33 (25%) infiltrated fat, and 10 (8%) entrapped skeletal muscle (all but 1 situated on the face). Nearly all tumors had a lobulated or micronodular architecture and were composed of nests and bundles of epithelioid to spindled cells with palely eosinophilic cytoplasm, often separated by dense hyaline collagen; 17 (13%) showed focally sheetlike areas, and 5 (4%) were notably plexiform. Myxoid stroma was observed in 38 (29%) tumors; 11 (8%) were predominantly myxoid. Five (4%) showed marked stromal hyalinization. Osteoclastic giant cells were seen in 20 (15%) cases. The mean mitotic rate was 3 per 10 high power fields; 28 (21%) had > or =5 per 10 high power fields. Most tumors showed mild cytologic atypia in the form of nuclear variability and small nucleoli; 33 (25%) contained notably pleomorphic cells. All tumors were reactive for NKI-C3, 110/123 (89%) expressed neuron-specific enolase, 73/127 (57%) showed at least focal staining for smooth muscle actin, and only 1 was focally desmin positive. All tumors were negative for S-100 protein. Follow-up ranged from 5 to 146 months (mean 44 mo). Ten tumors recurred locally (7 situated on the face), after a mean of 18 months; tumor had been marginally excised or had involved excision margins in all cases with available information. No other clinical or pathologic features correlated with recurrence. Cellular neurothekeomas have a predilection for the upper limbs and head and neck of pediatric and young adult females and rarely recur following incomplete excision. There is no good evidence that these lesions show nerve sheath differentiation and the nomenclature will likely change when the tumor cell lineage is better defined. Atypical histologic features (including pleomorphism, infiltration of subcutis, and a high mitotic rate) seem to have no clinical significance.

Neurothekeomas of the upper limb--case series and clinicopathological review

Neurothekeomas are rare, benign soft tissue tumours that are considered to be of nerve sheath origin. We present a case series of three patients who have neurothekeomas of the upper limb. There was a remarkably high tumour recurrence rate. The factors contributing to this outcome were studied and a clinicopathological review was performed.

Nerve tumors of the hand and upper extremity

Tumors of peripheral nerve origin are usually slow growing and minimally symptomatic, making differentiation from other soft tissue neoplasms difficult. Yet failure to recognize a nerve tumor may result in irreversible loss of neurologic function. This article provides current information on the history, pathologic identification, and treatment of upper extremity nerve tumors. Other neoplastic and tumor-like lesions that occur within the peripheral nerve are also considered.

Neurothekeoma: report of a case in an infant and review of the literature

Neurothekeomas (nerve sheath myxomas) are uncommon benign tumors of nerve sheath origin. We describe an infant with a neurothekeoma and review the literature of neurothekeomas in children and adults. Neurothekeomas have been reported in 292 patients whose ages have ranged from 15 months to 84 years. They occur twice as often in women as in men. Neurothekeomas were most commonly located on the upper extremities and the head and neck. They also occurred on the trunk, the lower extremities, and mucosa. Histologic variants of neurothekeomas include classical, cellular, and mixed tumors. Surgical excision was the most common treatment. Recurrences were attributed to an incomplete excision; treatment of these tumors is by complete excision. Neurothekeomas should be included in the differential diagnosis of dermal nodules in infants and children.

Neurothekeoma of the paranasal sinuses in a 3-year-old boy

Neurothekeoma is a benign soft tissue tumor commonly located on the skin. In this report, a 3-year-old boy presented with restricted right eye movement and decrease in visual acuity. The patient was found to have a 6-cm neurothekeoma involving the maxillary and ethmoid sinuses. To our knowledge, this is the first reported case of neurothekeoma with involvement of the maxillary and ethmoid sinuses. This uncommon lesion should be considered as the differential diagnosis of pediatric soft tissue tumors in the head and neck region.

Problematic pigmented lesions: approach to diagnosis

A number of pigmented lesions are difficult to classify and raise the possibility of a melanoma diagnosis. Care should be exercised to exclude non-melanocytic lesions, and benign melanocytic entities, both of which can mimic melanoma histologically. In addition, the possibility of the lesion being a melanoma variant or epidermotropic metastasis should be considered. There will still be some cases that are difficult to resolve. These usually fall into one of three categories: atypical junctional melanocytic lesion versus early melanoma; naevus versus naevoid melanoma; and atypical Spitz, cellular blue, and deep penetrating naevi versus thick melanoma. These will pose problems even for experts. The atypical Spitz lesions are perhaps the most important category because they tend to be from younger individuals, the differential diagnosis is thick melanoma, and there is no single discriminating histological feature.

Myxoma is not a single entity: a review of the concept of myxoma

Myxoid lesions can be subdivided into (1) mainstream myxomas of soft tissues, (2) mainstream myxomas located outside the soft tissue, (3) inadequately substantiated myxomas, (4) myxoid soft tissue tumors or lesions not regarded as myxomas, (5) myxoid fatty conditions, (6) other soft tissue lesions and tumors that are sometimes markedly myxoid, (7) other soft tissue tumors in which myxoid foci may be seen, and (8) nonneoplastic myxoid conditions of soft tissue. More than 60 such conditions are listed and the five entities regarded as mainstream soft tissue myxomas (namely, intramuscular myxoma, juxta-articular myxoma, superficial angiomyxoma, aggressive angiomyxoma, and myxoid neurothekeoma [myxoma of nerve sheath]) are reviewed in detail. Intramuscular myxoma is exclusively intramuscular, usually affects middle-aged women, is most commonly located in the thigh, and does not recur after simple excision. Multiple intramuscular myxomas are rare and are usually associated with monostotic or polyostotic fibrous dysplasia and Albright's syndrome. Juxta-articular myxoma histologically resembles an intramuscular myxoma, but involves periarticular tendons, ligaments, joint capsules, muscles, and even the subcutis of adults. It may be associated with osteoarthritis of the adjacent joint. Some 30% recur locally. Superficial angiomyxoma also has been called cutaneous myxoma. It affects all ages, with a peak incidence in the third and fourth decades; arises in the trunk, lower limb, head, and neck regions; and usually measures less than 5 cm in diameter. Epithelial components are present in approximately 25% of tumors. Approximately one third recur locally, but there have been no metastases. Patients with multiple lesions may have the Carney complex. Aggressive angiomyxoma usually arises in the pelvic and perineal regions and affects females seven times as often as males. Tumors usually measure 10 cm or more in diameter, invade surrounding tissues, and recur in approximately 50% of cases. None have metastasized. Myxoma of nerve sheath (the myxoid variant of neurothekeoma) preferentially affects the dermis and subcutis of the cervicofacial areas and shoulders of young women. Most patients are younger than 40 years; one third of them are in the second decade of life. The majority of tumors measure between 0.5 and 1.5 cm. Only three of 102 cases compiled from the two largest published series recurred; none metastasized. The different clinicopathologic features and behavior of these five mainstream myxomas indicate that myxoma is not a single entity.

Atypical or worrisome features in cellular neurothekeoma: a study of 10 cases

Cellular neurothekeoma is a recently characterized benign cutaneous neoplasm arising usually on the upper trunk or head and neck of children or young adults. Typical histology is that of a lobulated dermal tumor composed of spindle and epithelioid cells, arranged in fascicles and nests, lacking immunoreactivity for S-100 protein, but usually being NK1/C3 positive. We present 10 new cases of cellular neurothekeoma with atypical histologic features that have not been described previously and that suggested the possibility of malignancy. The age range of affected patients was 1 to 44 years (median, 20.5 years); sites included the head and neck (three cases), the upper limbs (two cases), the lower limbs (two cases), and the trunk (two cases). Atypical findings in individual cases included large size (up to 6 cm), deep penetration (extending into skeletal muscle or subcutaneous fat, or both), diffusely infiltrative borders, vascular invasion, high mitotic rate, and marked cytologic pleomorphism. Clinical follow-up was available in 7 of 10 cases. Although the atypical features raised concern about the biologic potential of these lesions, preliminary follow-up (1-5 years) has shown no recurrence and suggests that complete surgical excision of these lesions is curative. These new data expand the morphologic spectrum of cellular neurothekeoma.

Cellular 'neurothekeoma': an epithelioid variant of dermatofibroma?

AIMS

Cellular neurothekeoma is a rare benign cutaneous neoplasm with conflicting opinions regarding its histogenetic origin (nerve sheath, smooth muscle, myofibroblasts) as well as its relation to myxoid neurothekeoma (nerve sheath myxoma). The present series describes 15 cases whose clinicopathological features indicate a relationship to dermatofibroma.

METHODS AND RESULTS

In this retrospective clinicopathological study, the lesions preferentially occurred in adolescents to young adults on the upper half of the body, often clinically diagnosed as some kind of fibrohistiocytic tissue response. Besides characteristic whorled nests to fascicles of palely eosinophilic epithelioid cells, all lesions showed variable clues pointing to dermatofibroma: acanthosis, ill-defined storiform periphery, peripherally accentuated prominent sclerosis and lymphocytic demarcation/infiltration. Immunohistochemically, all cases were positive with NK1C3 (CD57), KiM1p and proliferating cell nuclear antigen, seven were positive for neurone specific enolase, five for factor XIIIa, six for smooth muscle specific actin and three for E9, an antimetallothionein marker. These findings are similar to those of conventional dermatofibromas, the variability of the profile being best explained by time cycle and function dependent changes. Ultrastructurally, two cases showed microfilaments, attachment plaques, prominent pinocytosis and focal remnants of basal lamina. A careful study of the data and photomicrographs from the literature reveals that in many cases similar conclusions could be reached. Obvious discrepancies are most likely due to the confusion with myxoid neurothekeoma, a well circumscribed, more spindly and myxoid, S100 positive lesion of Schwannian origin.

CONCLUSION

The appearance of dermatofibromas is markedly influenced by architectural, e.g. in deep penetrating dermatofibroma, and/or cellular/stromal criteria, e.g. in epithelioid cell histiocytoma or sclerosing dermatofibroma. Cellular neurothekeoma seems to be a variant of dermatofibromas with both architectural and cellular/stromal peculiarities, i.e. plexiform pattern, epithelioid cytology and stromal sclerosis.

Ultrastructural spectrum of cutaneous nerve sheath myxoma/cellular neurothekeoma

The histogenesis of cutaneous nerve sheath myxoma (NSM)/cellular neurothekeoma (CNT) is still controversial. In this study, we examined the ultrastructural features of 16 NSM (3 classical, 11 CNT, and 2 mixed NSM/CNT). We classified the cells into 4 groups ultrastructurally. Type I cells were undifferentiated polygonal cells with ovoid nuclei, cytoplasmic microfilaments, and occassionally with microfilament-associated dense bodies. In most cells, the cytoplasmic membrane showed focal membranous densities and occasional basal-lamina-like material. This cell type comprised approximately 90% of CNT. Type II cells were more differentiated, had ovoid or spindled shapes, were rich in intracytoplasmic filaments, and were surrounded by continuous basal lamina. These cells were consistent with Schwann cells and were present in the classical and mixed forms of NSM, and in a single case of CNT. Type III cells had features of perineurial cells and were relatively rare in classical NSM. Type IV cells resembled fibroblasts and were encountered in all variants of NSM. These results support the view that 1) the classical NSM has neural (mainly Schwann cell) differentiation, 2) CNT is predominantly composed of undifferentiated cells with partial features of Schwann cells, smooth muscle cells, myofibroblasts and fibroblasts, suggesting a divergent differentiation, and 3) CNT and NSM represent a histologic spectrum, but in CNT, the neural features are not fully expressed.

Nerve sheath myxoma (neurothekeoma) of the skin: light microscopic and immunohistochemical reappraisal of the cellular variant

Nerve sheath myxoma (NSM) is a rare cutaneous neoplasm, the histogenesis of which is controversial. Fifteen cases of NSM were studied by routine light microscopy and with a broad panel of immunohistochemical stains. NSM were classified into three groups based on cellularity, mucin content and growth pattern. 1) The hypocellular (myxoid) type (5/15 cases) showed frequent encapsulation or sharp circumscription. Immunohistochemically this type was strongly positive for S-100 protein and collagen type IV and variably positive for epithelial membrane antigen. 2) The cellular type (4/15 cases) had scant mucin and ill-defined nodular or infiltrating growth. Immunostaining showed positive reaction for neuron specific enolase (2/4), Leu-7 (1/4) and smooth muscle specific actin (2/4), and was negative with the other antibodies. 3) The "mixed type" (6/15 cases) had variable cellularity and mucin content with poor demarcation and variable immunolabeling. We conclude that: 1) there are major light microscopic and immunohistochemical differences between the classical hypocellular (myxoid) and the cellular forms of NSM (neurothekeoma); 2) while the immunohistochemical results support the presence of nerve sheath differentiation in the classical forms of NSM, and to some extent in the mixed forms, there is an absence of convincing evidence of neural differentiation in the cellular variant by either light microscopy or immunohistochemistry; 3) the variable immunophenotypes suggest that differentiation other than neural may take place in CNT.

Myxoma of the breast: report of a case with unique histological and immunohistochemical appearances

A case of myxoma of the breast is reported. The patient, a 19 year old Japanese woman, showed a lump in the left breast which had enlarged gradually over 3 years. A tumor measuring 5 x 5 x 4.5 cm was located mainly in the mammary parenchyma, but partially involved the overlying subcutaneous tissue. Histologically the tumor was multinodular and each nodule consisted of an abundant myxoid substance with a few spindle or stellate mesenchymal cells. The presence of hyaluronic acid was observed in the myxoid area, and a few constituent cells showed immunoreactivities for S-100 protein and alpha 1-antichymotrypsin. Electron microscopic studies revealed that some constituent cells looked like undifferentiated mesenchymal cells, while others showed a differentiation similar to fibroblast or histiocyte. These findings suggest that the constituent cells might derive from totipotential primitive mesenchymal cells.

Cellular 'neurothekeoma': an epithelioid variant of pilar leiomyoma? Morphological and immunohistochemical analysis of a series

Cellular neurothekeoma is a recently recognized benign cutaneous neoplasm, which is currently regarded as being of nerve sheath origin and is thought to represent a variant of conventional neurothekeoma (dermal nerve sheath myxoma). Nine new cases presenting predominantly in adolescents or young adults are described. Morphologically they were characterized by short fascicles or small nests of palely eosinophilic epithelioid or spindle-shaped cells which ramified in an ill-defined manner between dermal collagen bundles. Myxoid matrix was absent or sparse. Scattered normal mitoses and multinucleate giant cells were often present. Immunohistochemically all nine cases were strongly NK1/C3 positive, seven were weakly NSE positive and three were smooth muscle actin positive. Staining for S-100 protein, PGP 9.5, epithelial membrane antigen and desmin was negative in all cases. In view of its distinctive architecture and immunophenotype, both of which are totally different from conventional neurothekeoma, it is proposed that cellular 'neurothekeoma' is a separate discrete entity which may represent an epithelioid variant of pilar leiomyoma.

Immunohistochemical evaluation of oral myxoid lesions

Oral examples of neurothekeomas (nerve sheath myxomas), soft tissue myxomas, and focal mucinous and odontogenic myxomas were examined for selected markers. With the use of avidin-biotin complex staining procedures, these specimens of lesions were stained with antibodies to S-100 protein, neurospecific enolase, neurofilaments, desmin, and vimentin. Our results show that the use of immunohistochemical markers for these neural antigens can aid in distinguishing nerve sheath myxomas from other oral myxoid lesions.

Studies on the cellular origin of neurothekeoma: clinical, light microscopic, immunohistochemical, and ultrastructural observations

The clinical, histopathologic, and immunohistochemical features of 11 cases of neurothekeoma are reported. One case was examined by electron microscopy. The mean age of the patients was 27.1 years; the study comprised eight female and three male patients. Most lesions were nondescript papules and located on the upper part of the body, seven cases of neurothekeoma on the head. Eight cases were classified as cellular neurothekeoma on the basis of a striking fascicular pattern and three cases as myxomatous neurothekeoma because of prominent myxoid stromal change. All cellular neurothekeomas failed to express S-100 protein, whereas the three myxomatous types were strongly positive for this marker. Other than vimentin, there was no significant immunoreactivity with other immunohistochemical markers. Ultrastructural study of one case of cellular neurothekeoma was inconclusive for cell type although a perineurial origin could not be excluded. On the basis of these results, we conclude that cellular neurothekeoma differs from myxomatous neurothekeoma not only by clinical and histologic findings but also by immunoreactivity with S-100 protein. These findings also suggest the existence of two distinct subtypes of neurothekeoma and possible origin of the two variants of neurothekeoma from different cell types or at least variation in phenotypic expression of a common cell type. On the other hand, it cannot be excluded that these two variants are different stages in the natural history of neurothekeoma.

Digital pacinian neuroma: a distinctive hyperplastic lesion

Neural tumours composed solely of Pacinian corpuscles or showing focal Pacinian differentiation are extremely rare and have only occasionally been reported in the literature. All such lesions to date have been benign. Three lesions are described herein which presented as painful digital masses in middle-aged adults and which were composed of abnormal aggregates of morphologically mature Pacinian corpuscles and intervening small nerves. Only five similar cases have been previously recorded. Possible pathogenetic mechanisms of this unusual hyperplastic phenomenon are discussed.

Epithelial membrane antigen expression by the perineurial cell: further studies of peripheral nerve lesions

We have previously shown that a range of anti-epithelial membrane antigen monoclonal antibodies show immunoreactivity with the perineurial fibroblast, both in normal nerves and within a range of common peripheral nerve tumours. We have extended these observations by studying a further collection of peripheral nerve lesions, including some which have previously been thought to have an origin from the perineurial cell. The results provide further evidence that these antibodies reliably stain perineurial cells and that in conjunction with antisera to S-100 protein and neurofilaments, the relative contributions of the perineurial fibroblast, Schwann cell and neurone can be assessed within a nerve-related tumour/lesion. The perineurial fibroblast is an important component of some peripheral nerve lesions.

Nerve sheath myxoma of the breast. A light and electron microscopic, histochemical and immunohistochemical study

A nerve sheath myxoma involving the breast has been examined by light and electron microscopy, and by immunohistochemical and histochemical methods. Electron microscopically, cells with features indicative of Schwann cells, perineural cells and fibroblasts were identified in the tumour and S-100 protein and vimentin positivity was demonstrated in the tumour cells. The mucoid matrix stained positive for chondroitin-4 or 6-sulphate in keeping with a cartilaginous lesion. These findings are discussed in relation to the uncertain histogenesis and the differential diagnoses of the tumour in the breast.

A combined immunohistochemical and histochemical approach on the differential diagnosis of giant cell epiphyseal neoplasms

The histological similarities and the common localization are the main causes of difficulties concerning the differential diagnosis between giant cell tumor of bone and chondroblastoma. The purpose of the present study was to detect whether histochemistry and/or immunohistochemistry could help to make the distinction between these two entities easier. The study was based on cases of chondroblastoma and giant cell tumor of bone from patients in the 2nd and 3rd decades of life. Histochemical detection of special intracellular and extracellular components (glycogen, glycosaminoglycans) as well as immunohistochemical investigation using various tumor markers (S-100, NSE, a-1-ACT, lysozyme, fibronectin) were performed on parallel paraffin sections. The presence of abundant intracytoplasmic glycogen granules and the immunoreactivity of the cells of chondroblastoma with S-100 and NSE, together with the presence of acidic sulfated glycosaminoglycans in the stroma, could help the differential diagnosis of this tumor from giant cell tumor of bone.

S-100 protein and neuron specific enolase immunoreactivity of normal, hyperplastic and neoplastic chondrocytes in relation to the composition of the extracellular matrix

S-100 protein and neuron specific enolase (NSE) are no longer considered as specific cell markers indicating a neural origin. Since most of the cells displaying immunoreactivity for both markers also elaborate a stroma rich in chondroid or myxoid mucosubstances, we undertook the present study in order to clarify whether or not the positive immunoreaction is related to the composition of stromal glycosaminoglycans. The study was based on formalin fixed, paraffin embedded material comprising adult resting cartilage, reactive or hyperplastic cartilage, as well as benign and malignant chondroblastic tumors. Histochemical and immunohistochemical methods were applied on parallel sections with the following results: A positive immunoreactivity of the cartilage cells was always found to be related to the participation of chondroitine sulfate A and C in the stromal glycosaminoglycans. A NSE positive reaction was found in all cartilage cells displaying the characteristics of metabolically active cells. It is postulated that S-100 protein, as a calcium binding protein, might be involved in the cellular control mechanisms regulating the glycosaminoglycans-collagen interactions.

Fibrous hamartoma of infancy: a histochemical and immunohistochemical study

Fibrous hamartoma of infancy is an uncommon lesion, the histogenesis and biological nature of which are uncertain. Ten cases have been studied by light microscopy, mucin histochemistry and immunohistochemistry. The typical histological features are presented. The presence of hyaluronic acid and of chondroitin-4- and -6-sulphate and keratan sulphate has been demonstrated in different components of the tumour. Vimentin positivity was noted in the undifferentiated and fibroblastic components. The implications of these findings are discussed. Whether the lesion merits the designation of hamartoma or is, in fact, a benign neoplasm remains obscure.

Expression of epithelial membrane antigen in perineurial cells and their derivatives. An immunohistochemical study with multiple markers

Paraffin-embedded surgical pathology specimens from skin (5) and muscle (2) biopsies, from Morton's neuromas (3), traumatic neuromas (8), schwannomas (21), neurofibromas (12), and from one perineurioma and one neurothekeoma were studied by immunoperoxidase histochemistry and antibodies against epithelial membrane antigen (EMA), Leu 7 epitopes (Leu 7), S-100 protein (S-100) and cytokeratins. Normal, reactive and neoplastic perineurial cells stain consistently for EMA, whereas Schwann cells express Leu 7 and/or S-100 positivity. None of the immunoreactive cells stained for cytokeratin. Our findings indicate that perineurial and Schwann cells can easily be distinguished by their different patterns of immunoreactivity with the above markers.

Extraskeletal myxoid chondrosarcoma: a histochemical and immunohistochemical study

In reviewing a large series of soft tissue sarcomas, nine cases of extraskeletal myxoid chondrosarcoma have been retrieved. These tumours, which principally presented in middle-aged adults, have been examined histochemically to determine the heteroglycan content of their myxoid matrix and immunohistochemically for the presence of S-100 protein. The principal mucopolysaccharides identified were chondroitin-4 and 6-sulphate and keratan sulphate; each of the tumours was S-100 positive. The relevance of these findings to the histogenesis and differential diagnosis of these uncommon neoplasms is discussed.