Cutaneous nerves in cafe au lait spots with white halos in infants with neurofibromatosis. An electron microscopic study

BACKGROUND AND DESIGN

Although two cardinal skin manifestations of neurofibromatosis are cutaneous neurofibromas and cafe au lait spots, the pathogenesis of cafe au lait spots are very poorly known compared with that of cutaneous neurofibromas. Thus, the cafe au lait spots in two Japanese infants were clinically, histologically, and electron-microscopically investigated.

OBSERVATIONS

Some of the cafe au lait spots in the mongolian spots were surrounded by white halos. Histologically, in the cafe au lait spots, the epidermal basal cells had abundant melanin pigment, but macromelanosomes were not seen throughout the epidermis. In the white halo, the epidermal basal cells had a small amount of melanin pigment. Electron microscopically, the cafe au lait spots and their white halos had many subepidermal and intraepidermal nerves that belonged to free nerve endings. All the cutaneous nerves were mature. Some of the intraepidermal nerves had partially or completely naked axons that contacted tightly with the cytomembranes of the basal keratinocytes. Some of the axons in the subepidermal nerves showed degenerative changes only in the white halos. No ultrastructural pathologic changes were observed in the melanocytes, the epidermal keratinocytes, or melanosomes in those cells in the cafe au lait spots and their white halos; also, dermal melanocytes were absent in the both areas.

CONCLUSIONS

The increase of the cutaneous nerves and the absence of dermal melanocytes in the cafe au lait spots and their white halos may be considered as characteristic histologic cutaneous findings in infants with neurofibromatosis. However, no evidence indicates that the cutaneous nerves may participate closely in the pathogenesis of the white halos.

Exocrine pancreatic insufficiency and pancreatic fibrosis due to duodenal somatostatinoma in a patient with neurofibromatosis

A case of duodenal somatostatinoma is described in a patient with Von Recklinghausen neurofibromatosis. The patient presented with exocrine pancreatic insufficiency, probably due to distal obstruction of the pancreatic duct by the tumor. Preoperative evaluation with calcium-pentagastrin and tolbutamide stimulation tests were nondiagnostic. At laparotomy, local excision of the tumor was performed. Pathological findings were compatible with duodenal somatostatinoma, causing pancreatic fibrosis. Somatostatin extracted from the tumor coeluted with the somatostatin-14 standard on high performance liquid chromatography (HPLC).

Immunohistochemical localization of type I, III, IV, V, and VI collagens and laminin in neurofibroma and neurofibrosarcoma

By using antibodies to type I, III, IV, V, and VI collagens and laminin, we examined the localization of interstitial collagens and basement membrane components with indirect immunofluorescence and immunoelectron microscopy (IEM). Furthermore, the morphological changes of these collagens in malignant transformation were investigated. In neurofibroma, IEM showed type I, III, and V collagens to be present diffusely on cross-striated collagen fibrils, whereas type VI collagen was present between the fibrils. Type IV collagen and laminin were observed to surround tumor cells. In neurofibrosarcoma, tumor collagen bundles that reacted with antibodies to type I, III, V, and VI collagens were irregularly arranged. Immunofluorescent deposits that reacted with anti-type IV collagen and anti-laminin antibodies were decreased in number, showing a thin and sparse arrangement.

Segmental neurofibromatosis

Two patients had localized multiple cutaneous neurofibromas; one had bilateral involvement of the scalp and the other had true segmental neurofibromatosis. Other signs of neurofibromatosis were absent. Segmental neurofibromatosis may not be related to the generalized types of neurofibromatosis but may be a cutaneous hamartoma.

A case of neurofibrosarcoma associated with neurofibromatosis: light microscopic, ultrastructural, immunohistochemical and biochemical investigations

A case of neurofibrosarcoma (NFS) with neurofibromatosis was studied by light microscopic, ultrastructural, immunohistochemical and biochemical methods. Histologically, spindle-shaped tumor cells with atypical hyperchromatic nuclei were arranged in a fascicular or sheet-like fashion. Electron microscopic examination revealed discontinuous basement membrane-like structures. Immunohistochemical study revealed S100 protein alpha chains in tumor cells. A biochemical analysis showed large amounts of gangliosides (sialic acid 13.5 micrograms/g wet tissue weight) in tumors. GM3 and GD3 were the major components; these results were compatible with the NFS ganglioside patterns found in our previous study. Results confirmed the diagnosis of NFS and indicate that NFS clearly has some neuroectodermal characteristics and that Schwann cells may possibly be related to its origin.

Transplacental induction of peripheral nervous tumor in the Syrian golden hamster by N-nitroso-N-ethylurea. A new animal model for von Recklinghausen's neurofibromatosis

Multiple peripheral nervous tumors were induced in 45 of 60 (75.0%) Syrian golden hamsters by transplacental administration of N-ethyl-N-nitro-sourea. Moreover, melanomas, pheochromocytomas, and Wilms' tumors developed in six (10.0%), three (5.0%), and 13 (21.7%) animals, respectively. The histologic, immunohistochemical, and electron microscopic findings of the peripheral nervous tumors were similar to those of human neurofibroma, and their growth pattern and distribution resembled those of human von Recklinghausen's neurofibromatosis (VRNF). The occurrence of melanoma, pheochromocytoma, and proliferative foci of melanin-containing cells in neurofibroma suggests that the targets of ENU in hamsters are the neural crest-derived cells. With its high incidence of Wilms' tumor, the hamster with ENU-induced tumors is considered to be a good animal model for human neurocristopathy, including VRNF.

Perineurial cell tumor and the significance of the perineurial cells in neurofibroma

The authors attempted to clarify the exact cell components of neurofibroma by immunohistochemical and ultrastructural studies. Materials were randomly selected, 40 cases of neurilemoma and neurofibroma (-tosis) in addition to 2 cases of tumors composed exclusively of perineurial cells and three cases of normal peripheral nerve. The applied markers included antisera of S-100 protein for Schwann cells, blood coagulation factor XIIIa for endoneurial fibroblasts or perineurial cells, and laminin and collagen type IV for the basement membrane. S-100 protein was demonstrated only in normal or neoplastic Schwann cells, but not in perineurial cells. On the other hand, factor XIIIa was often recognized in endoneurial fibroblasts and perineurial cells, but not in Schwann cells. Neurofibroma was basically composed of a mixture of Schwann cells, perineurial cells, and endoneurial fibroblasts, the population of each type of cell differing according to the case and area within a given tumor. Perineurial cell tumor exclusively composed of perineurial cells, though rare, appears to be a definite entity, and its characteristic histological and ultrastructural features were described.

Ultrastructural localization of S-100 protein in neurofibroma

The nature of the cells in neurofibromas was studied by electron microscopy and immunoelectron-microscopic examination of S-100 protein. Ultrastructurally, all five neurofibromas studied were found to be composed of Schwann cells, perineurial cells, and intermediate cells, which had features of both perineurial cells and fibroblasts. The Schwann cells had complex, branched cytoplasmic processes and a continuous basal lamina. The perineurial cells were distinguishable from Schwann cells by the presence of numerous pinocytotic vesicles, unbranched slender cytoplasmic processes and a discontinuous basal lamina. The intermediate cells had no basal lamina, but were topographically related to Schwann cells and had a similar fine structure to that of perineurial cells. Thus, they seemed to be modified neoplastic perineurial cells. Immunoelectron-microscopic studies showed the presence of cells with and without S-100 protein in the neurofibromas: cells with S-100 protein resembled Schwann cells ultrastructurally, and those without S-100 protein were perineurial and intermediate cells. Some Schwann cells with S-100 protein in one neurofibroma had numerous pinocytotic vesicles characteristic of perineurial cells, suggesting that Schwann cells and perineurial cells are functional variants of the same cell type. Thus this study showed that neurofibromas were composed of Schwann cells with S-100 protein and perineurial and intermediate cells, including so-called endoneurial fibroblasts, without S-100 protein. Morphological and functional transition seems to occur between Schwann cells and perineurial cells, and between perineurial cells and intermediate cells.

Basement membrane proteins, interstitial collagens, and fibronectin in neurofibroma

The distribution and nature of extracellular matrix proteins in neurofibroma tissue was studied by indirect immunofluorescence, immunoelectron microscopy, immunoblotting, and rotary shadowing. The most striking feature was an extensive network of basement membranes localized mainly around Schwann cells and small blood vessels. The major components, collagen IV, laminin, and nidogen, were mainly deposited in the lamina densa. Some laminin and nidogen could be extracted with 0.5 M NaCl and were shown by electrophoresis to have the characteristic chain and fragment patterns described previously for these proteins isolated from the mouse Engelbreth-Holm-Swarm (EHS) sarcoma. Fragments of collagen IV and collagen VI were solubilized by limited proteolytic digestion and identified after rotary shadowing. The more remote interstitial regions of the tumor contained cross-striated collagen fibrils which were composed of collagen III (diameter, 20-30 nm) or collagen I (diameter, 40-50 nm). Collagen fibrils thicker than 80 nm were not found. The interstitial regions also contained collagen VI as a fine filamentous network near cells and between collagen fibrils. Deposits of fibronectin were rather small and showed a scattered distribution. The data indicate that Schwann cells contribute considerably to matrix production in neurofibroma which may therefore be a suitable model for studying basement membranes of neuroectodermal origin.

Neurofibromatous dermal hypoplasia: a clinical, pharmacological and ultrastructural study

Dermal hypoplasia is reported in three patients with neurofibromatosis. The areas of dermal hypoplasia failed to react to vasodilator stimuli and responded poorly to a vasoconstrictor stimulus. Histology of these lesions showed neurofibromatous tissue and at an ultrastructural level cells resembling perineurial cells were wrapped around dermal vessels. The poor vascular responses seen in these areas of neurofibromatous dermal hypoplasia might be due to the perineurial cells acting as a barrier to diffusion of the pharmacological agents and as a physical perivascular splint.

[Malignant schwannoma arising in Recklinghausen's disease--report of 4 cases]

Four cases of malignant schwannoma arising in Recklinghausen's disease are described. The 4 patients, aged 38, 41, 44 and 38, 2 men and 2 women, had up to child-head-sized tumors in the neck, back, axilla and retroperitoneum. Oncostatic chemotherapy and irradiation were ineffective against the malignant schwannoma. In three, surgically tumor-resected cases, local recurrence and rapid tumor growth occurred. Histologically, malignant schwannoma was characterized by the presence of a few collagen fibers among the tumor cells, but abundant argentaffin fibers. Numerous mast cells are frequently seen in neurofibroma, but almost never in malignant schwannoma. In Case 3, with mild atypism, tumor cells were positive for S100 protein.

Segmental neurofibromatosis

A child with segmental neurofibromatosis is reported. The clinical, histopathological and ultrastructural characteristics of this rare condition are described. This entity is considered to be a localized form of von Recklinghausen's disease. The aetiology is not clear, but somatic mutation in early embryonic development may be important.

The nature and origin of the melanin macroglobule

The melanin macroglobule (MMG), formerly called "macromelanosome," is a cytoplasmic spherical granule formed in the melanocyte, varying in size from one to several microns, much larger than normal ellipsoidal melanosomes. Although ultrastructural features of MMG have been adequately described in the past, there has been a disagreement about the formation process of MMG. In order to further elucidate the nature and origin of MMG, electron microscopic studies were conducted in several pigmentary disorders. Our findings included: (1) The most remarkable characteristics of MMG are (a) the pleomorphism of their internal structure and (b) the variation of their size. (2) MMG do not represent true melanosomes but unique forms of autolysosomes resulting from the fusion of autophagosomes (containing various numbers of melanosomes) with primary and/or secondary lysosomes. (3) MMG are retained within melanocytes or transferred to keratinocytes and to Langerhans cells in the epidermis, and to macrophages in the dermis in any of their developmental stages. After transfer, MMG can fuse with other heterolysosomes and probably increase in size in these cells. We regard melanosome complexes as but one step in an autophagic process within melanocytes which can, on occasion, produce MMG as residual bodies.

So-called glandular schwannoma: ependymal differentiation in a case

A cervical root tumor in a patient with neurofibromatosis showed a biphasic pattern of spindle and epitheloid cells with prominent "gland" formation, characteristic of the so-called glandular schwannoma. Electron microscopy and histochemistry of the "glands" disclosed features consistent with an ependymal differentiation. It is noted that there is a curious preferential association of ependymal lesions and neurofibromatosis, the pathogenesis of which is not understood.

Neurofibromatosis tumor and skin cells in culture. II. Structural proteins with special reference to the cytoskeletal and cell surface components

Structural proteins of cultured neurofibromatosis (NF) tumor and skin cells were studied with reference to control skin fibroblasts. In polyacrylamide gel electrophoresis (PAGE)/fluorography the banding patterns of the cell lysates were markedly similar. NF tumor cells, however, produced a 60 kD band with a stronger and a 48 kD band with a lighter protein staining and metabolic labeling intensity. Furthermore, skin cells were also characterized by a 26 kD protein and the tumor cells by a 22 kD protein with high metabolic labeling intensity. Neuraminidase/galactose oxidase/NaB3H4-labeled NF skin and control skin cells possessed a 220 kD protein that was less intensively labeled in the tumor cells. The banding pattern of the skin cells was also characterized by a protein with slightly lower molecular weight (86 kD) than that of the tumor cell lysates (90 kD). In all cell lines studied indirect immunofluorescence stainings revealed bright arrays of vimentin type intermediary filaments but no desmin, cytokeratin, glial fibrillary acidic protein (GFAP), or neurofilament proteins. NF skin and control skin cells possessed well developed actin-containing bundles of microfilaments, while those of the tumor cells lacked a typical stress-fiber organization. The general morphology of the tumor cell cultures was also irregular. Transmission electron microscopy revealed no basic differences in the structure of intermediary filaments or microfilaments. The present data provide basic knowledge of neurofibromatosis skin and tumor cells and demonstrate that cultured cells originating from neurofibromas are defective in both their intracellular and extracellular organization.

Electron microscopy in the diagnosis of malignant schwannomas. A report of six cases

The diagnosis of malignant schwannoma may be difficult or impossible by light microscopy alone, if the neoplasm is poorly differentiated and if there is no clinical evidence for its arising from a nerve-trunk. Six cases of malignant schwannoma in which electron microscopy confirmed or established the diagnosis are reported. In four cases, the anatomic origin of the neoplasm arising from a large nerve was demonstrated at the time of operation, and in one of these the patient had von Recklinghausen's disease. In three of the four cases, as well as in the fifth case, in which the tumor was associated with an overlying malignant melanoma, the distinctive schwannoma patterns of Antoni types A and B tissue were absent. In the sixth case, there were no clinical clues as to nerve sheath origin, but both the light and electron microscopic features of the neoplasm were very characteristic of Schwann cell derivation. The most consistently present, ultrastructural features of malignant schwannoma are the spindle shape of the cells and the terminal cytoplasmic processes. If the processes show intertwining and if lateral cell borders are interdigitated, the diagnosis is more readily confirmed. Likewise, basal lamina is an important diagnostic feature but may be scant and focal in the very cellular and less differentiated tumors. Microfilaments are usually present, albeit in varying numbers, and they do not form the dense bodies seen in smooth muscle cells. Other diagnostically useful, but less consistent characteristics include microtubules, primary and secondary lysosomes, and dense-core type granules. Long-spacing collagen was present in only one case and in none of those reviewed from the literature. This is also an important finding. It is probable that most malignant nerve sheath neoplasms arise from Schwann cells, rather than from fibroblasts or perinurial cells, but electron microscopy often will be necessary to confirm this impression.

Choroidal ganglioneuroma in neurofibromatosis

A twenty-one year old female with previously unsuspected neurofibromatosis presented for evaluation of a blind painful eye. Histopathologic examination of the enucleated specimen revealed choroidal thickening with ovoid bodies and proliferation of connective tissue with pigment-containing cells and ganglion-like cells. Electron microscopic study of the latter cell population revealed typical morphologic features of ganglion cells, including numerous electron-dense intracellular granules and an abundance of mitochondria and rough endoplasmic reticulum. These pathologic findings were interpreted as consistent with the diagnosis of choroidal ganglioneuroma occurring in the context of ocular neurofibromatosis. The literature concerning this unusual tumor is reviewed and the possible relationship of this lesion to neurofibromatosis and other disorders of neural cresent proliferation are briefly discussed.

Neurofibromatosis tumor and skin cells in culture

Skin fibroblasts and tumor cells were cultured from four patients with peripheral von Recklinghausen's neurofibromatosis (NF). The cell type enriched in culture from the tumors carried the fibroblastic Thy 1.1. cell surface antigen and produced fibronectin, like fibroblasts from skin of NF-patients or from control persons. In electron micrographs the NF tumor and NF skin cells were similar to the control skin fibroblasts; elongated in shape, contained tubular mitochondria, variable amounts of granular endoplasmic reticulum, numerous lysosomal inclusion bodies and collections of 5 nm filaments. Trypsinized cells were fractionated with centrifugation in a Percoll density gradient. All cell lines produced only one sharp band of viable cells at the buoyant density of 1.03. Compared with the NF skin or control skin fibroblasts the NF tumor cells, however, produced a less well organized peri- and extracellular matrix estimated from fibronectin fluorescence. The nuclear sizes were measured from photographs of the cultures. The nuclei of all four tumor cell lines were larger than those of the skin fibroblasts of the corresponding patients. Neurofibromatosis tumor cells thus resemble skin fibroblasts in their density and in some ultrastructural properties but are different in their growth pattern and synthetic functions.

Ovoid bodies in choroidal neurofibromatosis

We studied the ultrastructure of the ovoid bodies in choroidal neurofibromatosis. Ovoid bodies consisted of groups of the same kind of elongated cells arranged in lamellar patterns. The elongated cell was characterized by a fragmented circumferential basal lamina, groups of pinocytotic vesicles, a desmosomelike intercellular contact, and intimate contact with axons. These findings suggest that elongated cells are proliferated Schwann's cells and ovoid bodies do not correspond with real sensory nerve end organs; rather, they are enlarged peripheral nerves due to neoplastic hyperplasia of Schwann's cells around axons.

Granular cell variant of neurofibromatosis: ultrastructure of benign and malignant tumors

A case of neurofibromatosis with a metastasizing malignant tumor is presented. The benign lesions were identified by light microscopy as neurofibromas containing granular cells typical of granular cell tumors. The malignant tumor was classified as a malignant granular cell tumor. Ultrastructural studies demonstrated common histogenetic and subcellular features of the benign and malignant tissues. The case is the first reported in which granular cells are seen in the lesions. The typical granular cell morphologic features of the malignant lesion support the concept of Schwann cell derivation of this group of tumors.

Blue-red macules and pseudoatrophic macules: additional cutaneous signs in neurofibromatosis

Blue-red macules and pseudoatrophic macules are characteristic skin lesions of neurofibromatosis that have been infrequently mentioned in the recent literature. The histologic characteristics of the blue-red macules show thick-walled blood vessels located mainly in the papillary dermis and often overlying subcutaneous neurofibromatous tissue. The histologic characteristics of the pseudoatrophic macules show a reduction in collagen in the reticular dermis, with diffuse replacement by neuroid tissue. These clinical signs can be detected early in the course of the disease and are useful in establishing an early diagnosis.

Electron microscopy in the diagnosis of malignant schwannoma

Fifteen malignant schwannomas were examined by light and electron microscopy. Five tumors arose in patients with neurofibromatosis and five were contiguous with a peripheral nerve (Group I). Five tumors met neither of these generally accepted diagnostic criteria but were light microscopically seen as compatible with malignant schwannoma when examined under light microscope (Group II). In the better differentiated areas of Group I lesions, long, overlapping, tightly packed cytoplasmic processes were parallel to homogeneous flocculent material, occasionally assuming a linear appearance suggesting basal lamina. In Group II, similar cytoplasmic processes were present but the extracellular material was less extensive and had a less obvious relationship to the plasma membrane. In neither group were fine intracytoplasmic filaments prominent. Malignant schwann cells are seldom as ultrastructurally differentiated as their benign counterparts. Nevertheless, within the context of well-studied light microscopy and the sampling error inherent in ultrastructural examination, electron microscopy can support the diagnosis of malignant schwannoma.

The architecture of optic nerve gliomas with and without neurofibromatosis

A retrospective clinicopathologic study of 34 patients with optic nerve glioma disclosed two important architectural tumor forms: circumferential-perineural pattern featuring tumor eruption and proliferation in the subarachnoid space correlating with the presence of neurofibromatosis, and an expansile-intraneural pattern correlating with the absence of neurofibromatosis. The 18 patients with neurofibromatosis had a mean age of 4.9 years at presentation and tended to be younger than the 16 patients without neurfibromatosis (mean age, 12 years). Instead of "arachnoidal hyperplasia," electron microscopic studies in the electron microscopic studies in the circumferential-perineural pattern showed tumor astrocytes admixed with reactive meningothelial cells, fibroblasts, and collagen in distended subarachnoid space. Florid invasion of the leptomeninges (arachnoidal gliomatosis) exhibited by many optic nerve gliomas in neurofibromatosis suggests that they are true neoplasms rather than hamartomas, but their frequent location in the distal anterior visual pathway often confers a good clinical prognosis.

Study on the ultrastructure and acetylcholinesterase activity in von Recklinghausen's neurofibromatosis

The cutaneous nodules obtained from seven patients with von Recklinghausen's neurofibromatosis were investigated by electron microscopy, and ultrastructural localization of acetylcholinesterase activity was demonstrated in the nerve fibers of this tumor for the first time using Karnovsky's thiocholine method. The enzymatic activity was mainly found in unmyelinated fibers, exactly associated with their axonal membranes, the interspace between the apposing axonal and Schwann cell membrane, and some different mesaxons, which indicated their cholinergic nature. Almost all myelinated fibers and some unmyelinated fibers did not possess the activity. The relationship between axon and Schwann cell was quite similar to that of normal peripheral nervous system, but two striking alterations of the nerves existed: One is the dissociation of unmyelinated fibers, and the other is the degenerative changes of the axon and the myelin sheath. As the evidence of schwannian proliferation, onion bulb formations and collagen pockets were observed. Some signs of fibroblastic proliferation were also found. From the present study and the review of the literature, the probable histogenesis of this disease was discussed.

Spheroidal filamentous inclusion body cells in von Recklinghausen's disease

Cells with spheroidal filamentous cytoplasmic bodies, distinctive by both light and electron microscopy, were found in a neoplasm arising from the sciatic nerve of a patient with von Recklinghausen's disease. Tissue fixed with formalin and embedded in paraffin for three years was deparaffinized, reprocessed, and examined with the electron microscope. The morphology of the spheroidal body cells, the close resemblance to erythrophagocytosis, and the possible significance of the changes are discussed.