Subungual exostoses—clinicopathological and ultrastructural studies of three cases

Three patients with subungual exostoses, two involving the great toe and one the fourth toe, are presented. Local excision was performed, and the specimens were processed for light and electron microscopy. Light-microscopic study revealed that the tumours consisted of a proliferative fibrocartilaginous cap that merged into mature trabecular bone at its base. Electron-microscopic examination revealed that the tumour was composed of two types of cells: one was rich in cell organelles including rough endoplasmic reticulum, well-developed Golgi apparatus, and glycogen granules; the other cell had few such cell organelles. The former cells seemed to be osteoblasts actively engaged in bone formation, and the latter to be osteocytes related to those situated deeper in bone matrix in normal bone. However, ossification or calcification in subungual exostosis is rather casual, and osteocytes in this disorder may lack the capacity to elaborate compact bone.     

The specialized junctions between Merkel cell and neurite: an electron microscopic study.

Longitudinal serial sections of one half of the entire sinus hair of a mouse were examined by the electron microscope. Three neurites entering the outer root sheath from the perifollicular blood sinus were encountered. These were separate nerve trunks from those connected with perifollicular tactile nerve endings and exclusively innervated intrafollicular Merkel cells. Two types of specialized junctions were observed at the contact regions between Merkel cell plasma membrane and neurite plasma membrane: (i) desmosome-like structures in which small clear vesicles and/or the large cored vesicles of neurite and thicker membrane (post-synaptic?) of apposed Merkel cell were found ant (ii) synapse-like structures in which Merkel cell granules were concentrated near the plasma membrane and the membrane of the apposed neurite was usually thicker (post-synaptic?). In some of the synapse-like junctions the limiting membrane of Merkel cell granules fused with the Merkel cell plasma membrane and its content seemed to be discharged into the intercellular space. This suggested actual exocytotic secretion of Merkel cell granules. Juxtaposition of 2 types of junctions, i.e. (i) and (ii) above, was also found. This suggested the possibility that the reciprocal synapse would be present between Merkel cells and afferent neurites.     

Structural diversity of mast cell granules in black and white skin

BACKGROUND: There are conflicting reports of structural differences between black and white skin, other than pigmentary differences. OBJECTIVES: To evaluate differences in mast cells between black and white skin. METHODS: Biopsies of normal buttock skin were obtained from four African-American males (29.2 +/- 3.0 years old) and four Caucasian males (29.4 +/- 1.2 years old) and processed routinely for electron microscopy. For the quantitative assessment of mast cell granules, five electron micrographs at a final magnification of x 53,700 were analysed for each individual, using a computer-assisted image analyser. More than 10 granules per cell, and a total of 1210 granules, were evaluated for their internal structures. RESULTS: Mast cells in black skin contained larger granules than those in white skin (P < 0.0001). In black skin, fusion of granules seemed to account for the larger sizes. The percentage of granule matrix occupied by curved lamellae was higher in white skin, whereas parallel-linear striations were more frequent in black skin (P < 0.05). The subgranular distribution of the mast cell proteases, tryptase and cathepsin G, were evaluated by immunoelectron microscopy. Tryptase reactivity was localized preferentially over the parallel-linear striations and partially over the dark amorphous subregions within granules of black skin, whereas it was confined to the peripheral area of granules, including curved lamellae, in white skin. Cathepsin G reactivity was more intense over the electron-dense amorphous areas in both groups, while parallel-linear striations in black skin and curved lamellae in white skin were negative. CONCLUSIONS: This study has confirmed ultrastructural differences in mast cell granules between black and white skin, which may be of functional importance.     

Adult human skin maintained in organ culture. II. The ultrastructure of the cellular compartment of connective tissue

Dermal cells maintained in cultured human skin explants for up to 10 weeks were studied by electron microscopy. Common findings in the cell organelles were: 1) altered nuclear shapes and numerous nuclear bodies; 2) reduced rough endoplasmic reticulum; 3) a prominent Golgi complex; and 4) an increasing number of free ribosomes, mitochondria, glycogen granules, lysosomes and lipid droplets. The individual types of dermal cells showed various cytoplasmic changes according to duration of the culture. The fibroblasts displayed a moderately developed rough endoplasmic reticulum. The macrophages were filled up with lysosomes and residual bodies. The mast cells showed typical as well as atypical granules. The smooth muscle cells had a variable content of myofilaments. The pericytes and the smooth muscle cells, both surrounded by a basal lamina, became increasingly difficult to discern from each other as a consequence of the decreasing number of myofilaments in the latter. The endothelial cells were recognized because of the preserved blood vessel architecture. Besides the above-mentioned cell types, two other types appeared with the culture time. The unidentifiable cells were characterized by dense zones of the cell membrane and an adjacent extracellular basal lamina-like material. This cell type may be derived from the pericytes of the small blood vessels. The primitive cells had a large rounded nucleus and a cytoplasm with few organelles. This cell type is assumed to represent a precursor cell common to various cell types.     

Langerhans' Cells of Elderly Patients with Decubital Ulcers

An ultrastructural and morphometric study compared Langerhans' cells in sacral epidermis, 8–10 cm from the lesion of patients (mean age 70) with decubital ulcers, with those in the patients' own normal epidermis from the upper leg and with those in the epidermis from the upper leg of normal age-matched volunteers. The Langerhans' cell section area was significantly lower in patients' control leg epidermis (25.86 ± 2.29 μm²) than in that from normal controls (35.74 ± 3.76 μm²) or that from patients' sacral epidermis near the lesion (41.26 ± 3.45). The number of Langerhans' cell granules was higher in control leg epidermis of patients (10.22 ± 1.26) and was significantly higher in lesioned sacral epidermis (12.94 ± 1.90) than in normal controls (6.97 ± 1.47). In Langerhans' cells in patients' epidermis, formative stages of Langerhans' cell granules were observed. The findings may indicate that Langerhans' cells in patients' epidermis are in an active state.     

Pagetoid Merkel cell carcinoma: epidermal origin of the tumor

We report a case of intraepidermal Merkel cell carcinoma which occurred on the face of a 76-year-old white male. This slow-growing tumor was mostly confined in the epidermis and pilosebaceous apparatus where tumor cells spread in a pagetoid fashion forming tumor cell nests. Histologically it resembled a superficial spreading melanoma. A heavy lymphocytic infiltration was seen beneath the epidermal lesion as is often seen in pagetoid melanomas. Histochemical and ultrastructural features such as the presence of cytokeratin 20, synaptophysin, neuron specific enolase, desmosomes, and dense cored granules confirmed the diagnosis of Merkel cell carcinoma. Occasional mitotic cells and many apoptotic cells were found in the tumor. Dylon positive, amyloid depositions were seen in the lower epidermis and papillary dermis; they were probably derived from apoptotic tumor cells. It was thought that apoptosis limited the speed of growth of this tumor. We believe that this is probably the most convincing case of intraepidermal Merkel cell carcinoma originating from epidermal Merkel cells or its precursors (stem cells).     

A morphometric study of alterations in rough endoplasmic reticulum during differentiation in stratified squamous epithelium

Summary Stereological techniques were applied to investigate several structural parameters characterising the rough endoplasmic reticulum (RER) during differentiation in hamster cheek-pouch epithelium. Mucosal samples from five Syrian golden hamsters were obtained and processed for electron microscopy. Following a strict sampling regime, micrographs were obtained from defined basal, spinous and granular layers, and subjected to stereological point and intersection counting procedures. This enabled volume and surface densities, and volume-to-surface ratios of RER to be determined for each cellular layer. From previous estimaes of the mean cytoplasmic volume of the average basal, spinous and granular cell in this tissue, it was possible to calculate the absolute volume and surface area of RER present in these average cells. Both volume and surface densities of RER decreased between basal and granular layers, whereas the total volume and surface area present in the average spinous and granular cell were both higher than in the average basal cell. These data suggest that RER is being synthesised during epithelial differentiation. In view of the role of the RER in the production of exportable proteins, it is possible that increased amounts of this organelle are required to synthesise the enzymes and glycoproteins found in membrane-coating granules, since these are also seen with increasing frequency in successively higher strata.     

Rod-shaped bodies resembling birbeck granule-like structures in endothelial cells of dermal capillaries in generalized granuloma annulare

A previous study demonstrated that, in generalized granuloma annulare in the epidermis, the Langerhans' cell section area and the number of Langerhans' cell granules or Birbeck granules per cell section were increased, suggesting an active state of these Langerhans' cells. Reexamination by transmission electron microscopy of the same tissue, but in samples also containing dermal tissue, from the same subjects revealed endothelial cells with rod-shaped bodies resembling Birbeck granules or Birbeck granule-like structures. This finding has not been previously described in blood vessels of human skin and is described here.     

Dermal dendrocytes FXIIIA+ phagocytizing extruded mast cell granules in drug‐induced acute urticaria

Background Few authors have been attempting between mast cells and dermal dendrocytes interactions on urticaria. Objective To describe the extruded mast cell granules and dermal dendrocytes in drug‐induced acute urticaria. Methods Seven patients with drug‐induced acute urticaria were enrolled in the study. We token skin biopsies of urticaria lesion and perilesional skin. The 14 fragments collected were processed to immunogold electron microscopy using single stains to tryptase and FXIIIa, besides double immunogold labeling with both. Results Some sections demonstrated mast cells in degranulation process, both in anaphylactic and piecemeal degranulation types. After double immunogold staining, 10 nm (FXIIIa) and 15 nm (Tryptase) gold particles were present together over the granules in mast cells indicating that tryptase and FXIIIa are each localized within the granules of these cells. Interestingly, we found a strong evidence of than the exocytosed mast cell granules contents both FXIIIa and tryptase immunolabeled are phagocytized by dermal dendrocytes. Conclusions The current observations provide morphological evidence that the exocytosis‐phagocytosis mechanisms of mast cell granules represents one pathophysiological example of mast cells‐dermal dendrocytes interactions in urticaria.     

The innermost cell layer of the outer root sheath in anagen hair follicle: Light and electron microscopic study

Summary To investigate cell differentiation in the outer root sheath (ORS) of the human anagen hair follicle, scalp skin specimens from individuals with normal hair were examined using light and electron microscopes. In the bulbar portion, the ORS was composed of two cell layers. The cells in the outer layer gradually increased in number upwards and finally underwent so-called trichilemmal keratinization, which proceeded toward the hair canal. On the other hand, the inner cells in the bulb formed a single cell layer along the outside of Henle's layer during cell differentiation; this unique layer was referred to as the innermost cell (IMC) layer of the ORS. With the use of hematoxylin and eosin stain, at the suprabulbar portion, where Henle's cells were keratinizing, an eosinophilic substance was deposited in the inner (Henle's) side of the IMC cytoplasm. The IMCs gradually became entirely eosinophilic and often produced keratohyaline granules. Ultrastructurally, the IMCs of the ORS showed an oblong shape forming a regularly arranged single-cell layer along the keratinizing Henle's layer and accumulated tonofilaments in the cytoplasm. They produced a few small electron-dense keratohyaline granules and were keratinized at the level at which Henle's layer still preserved its cell structure. From these findings, it is suggested that there are two types of keratinization of the ORS: trichilemmal keratinization and IMC keratinization.     

AN ULTRASTRUCTURAL STUDY OF STEATOCYSTOMA MULTIPLEX AND THE NORMAL PILOSEBACEOUS APPARATUS

In order to clarify the site(s) from which steatocystoma multiplex (SCM) originates, five cases of SCM and the normal pilosebaceous apparatus were comparatively examined by electron microscopy. The cyst-wall of SCM, consisting either of flattened or of undulating horny layer, contained a small number of tonofilaments, desmosomes, and tiny spherical keratohyalin granules. There were variable numbers of lamellar granules which were also frequently observed in the intercellular spaces of the horny layer. Three of the SCM cases included sebaceous cells. The contents of the cysts were mostly amorphous and short-fibrillar, but sometimes keratinized cells and remnants of lamellar granules were observed. These findings were analogous to those of the normal pilosebaceous apparatus from the level of the lower part of the infundibulum to the outer root sheath Via the sebaceous duct, and were specifically more analogous to those of the sebaceous duct.     

Differences in hair follicle dermal papilla volume are due to extracellular matrix volume and cell number: implications for the control of hair follicle size and androgen responses

The size of a hair follicle is thought to be determined by the volume of its dermal papilla. The volume of the dermal papilla depends on the number of cells it contains and on the volume of the extracellular matrix. To establish which of these two variables is related to differences in hair follicle size we performed a stereologic study on 235 hair follicles from different sites, including male facial skin (beard), female facial skin, and scalp. In facial follicles there was a strong correlation between the area of the hair cortex and the volume of the dermal papilla. The area of the hair cortex also correlated with the number of cells in the dermal papilla and with the volume of dermal papilla per cell. In scalp hair follicles, where there was a smaller range of sizes, the correlations between these variables were weaker. In large male facial follicles the mean total dermal papilla volume was almost 40-fold higher than in vellus follicles from female facial skin. This difference was associated with a mean 17-fold greater number of cells in the dermal papilla and a 2.4-fold greater volume associated with each cell. Intermediate results were obtained in scalp follicles. In many regions of the skin hair follicles enlarge in response to androgens during adult life hair. Our results imply that the increase in the volume of the dermal papilla in these follicles is due to an increase in the number of cells, either through proliferation or through the migration of cells from the follicular dermal sheath, and to an increase in the amount of extracellular matrix per cell. As androgens are thought to act primarily on the dermal papilla, these changes may have a direct bearing on the mechanism of androgen-mediated alterations in hair follicle size.     

Blastoid NK cell leukemia/lymphoma with cutaneous involvement

Malignant neoplasms from natural killer (NK) cells are characterized by their positivity for CD56 and absence of monoclonal TCR gene rearrangement. Recently, they have been classified into four main types (nasal and nasal-type NK cell lymphoma, aggressive NK cell leukemia/lymphoma, and blastoid NK cell leukemia/lymphoma), based on clinical features, racial predisposition, presence of azurophilic granules, immunophenotype and association with Epstein-Barr virus (EBV) infection. A 72-year-old Caucasian man presented with a malignant neoplasm comprised of blastoid cells without azurophilic granules in the Giemsa stain, with positivity for CD2, CD4, HLA-DR, CD45 and CD56, and negativity for CD3 (surface and cytoplasmic) and CD5. In situ hybridization for EBV and PCR analysis of rearrangement of the T cell receptor gene were negative. Based on these results, a diagnosis of blastoid NK cell lymphoma was made. In this case the first clinical manifestations were the cutaneous lesions, and, although the disease was already advanced at the diagnosis, the patient responded completely to the treatment and remains asymptomatic 14 months after diagnosis.     

Mast cells in solitary glomus tumors: a possible algogenic role.

Mast cells in three cases of solitary glomus tumor were examined by light and electron microscopy. As seen by light microscopy, a number of round, oval or elongated mast cells were distributed throughout the stromal connective tissue and showed slight or moderate metachromasia when stained with toluidine blue (pH 4.1). Electron microscopy revealed various types and degrees of degranulation of mast cell granules, and also disclosed a close correlation between mast cells and non-myelinated nerve fibers. These findings suggest that mast cells may play an algogenic role in solitary glomus tumors, probably mediated by the contents, mainly histamine, concentrated in their granules.     

A STUDY OF MULTICENTRIC RETICULOHISTIOCYTOSIS (LIPOID DERMATOARTHRITIS)

A case of multicentric reticulohistiocytosis is presented, with typical clinical, roentgenologic, and histologic features. The characteristic giant cells were seen in skin nodules, mucosal nodules, synovial and bony lesions of the joints, and tenosynovial cysts. Corticosteroid therapy produced a subjective improvement, but the arthritis mutilans did not improve. Laboratory studies showed iron-deficiency anemia, hypertriglyceridemia (hyperprebetalipo-proteinemia), a low response to the unstimulated and stimulated nitroblue tetrazolium test of neutrophils, and a decreased activity in the glucose-6-phosphate dehydrogenase of polimorphonuclear leucocytes before corticosteroid therapy. The histochemical examination of the material in the giant cells showed a lipid (a phospholipid and a neutral fat), and a polysaccharide attached to a protein (a muco- or glycoprotein). Electron microscopic studies of the giant cells indicated that their cytoplasm contained numerous dense granules clustered in the vicinity of the Golgi apparatus. In some areas the granules appeared to be developing from the Golgi vesicles and cisternas. It seemed likely that the storage material was produced within the giant cells. We also discussed the pathogenesis of this disorder.     

大细胞棘皮瘤一例

患者,男,62岁。右上肢斑块伴轻度瘙痒半年余。组织病理检查：网篮状角化过度,颗粒层细胞角质透明颗粒增多,各层细胞体积增大,可见轻度异型性,基底层色素增多,皮突延长,部分呈芽蕾状,与两侧正常表皮界限清楚,真皮浅层灶状单一核细胞浸润。诊断：大细胞棘皮瘤。行手术切除。     

QUANTITATIVE ULTRASTRUCTURAL VARIATIONS BETWEEN PITYROSPORUM OVALE AND P. ORBICULARE BASED ON SERIAL SECTION ELECTRON MICROSCOPY

From serial section electron micrographs, the ultrastructural cytology of whole cells of Pityrosporum ovale and P. orbiculare was analyzed volumetrically and illustrated in three-dimensional images. Cells cultured on sodium taurocholate medium were fixed in both glutaraldehyde and potassium permanganate solutions and imbedded in Vestopal for serial sectioning. The volume of the cell, mitochondria and nucleus was obtained by measurements of successive sections through whole cells. The sections of one cell were built in a solid model. The average number of mitochondria in the cells of P. ovale was 23 and in P. orbiculare 2.6 per cell. The volume of the mitochondria was from 14% to 37% of the cell volume. The mitochondria of P. orbiculare appear to increase in size with cell volume, whereas in P. ovale, there may be an increase in number rather than in size. Two types of cellular bodies, one electron light and one electron dense, present in each species, also showed differences in size and number. The volume of the nucleus was 6 to 9% of the cell volume. The serial section analysis points to differences in mitochondrial biogenesis which may be of taxonomic value in separating the two species of Pityrosporutn.     

Quantitative evaluation of two distinct cell populations expressing HLA-DR antigens in normal human epidermis

HLA-DR antigens are expressed only by Langerhans cells (LC) and indeterminate cells (IC) in normal human epidermis. Indirect immunofluorescence and ultrastructural immunogold labelling were used to study the HLA-DR expression by means of two anti-DR monoclonal antibodies (MCA). Freshly dispersed DR-positive epidermal cells expressed different densities of DR antigens on their membrane surface. Approximately 25% of DR-positive cells were strongly labelled by anti-DR-MCA and 75% were weakly stained. After 18 h in complete culture medium before labelling no significant difference in these percentages was observed. The lymphoid-like LC-enriched cells obtained by Ficoll-Hypaque centrifugation also had two populations of DR-positive cells: strongly labelled cells (30.8%) and weakly labelled cells (69.2%). DR-positive cells may be divided into two types according to the density of DR sites on their cell membrane: (I) type DR+ shows weak surface labelling by gold particles (8.8 +/- 3.0 gold particles/micron) and has cytoplasmic Birbeck granules, identifying such cells as typical Langerhans cells; (2) type DR shows strong membrane immunogold labelling (38.9 +/- 4.6 gold particles/micron) and may or may not contain Birbeck granules. The gold particles bound to the cell membrane were used to quantify the number of HLA-DR sites expressed on each cell type: 1 X 10(5) sites on DR+ cells and 5 X 10(5) on DR cells.     

Melanin content and distribution in the surface corneocyte with skin phototypes

Summary An individual's sensitivity to sunlight is traditionally assessed by the Boston or Fitzpatrick classification of skin type. The ability to tan depends, to some degree, on the melanin content of the epidermis. In the study reported here, surface corneocytes in exposed skin and unexposed skin have been assessed using a surface stripping slide mounting technique and an Optomax V image analyser, with which the percentage of corneocyte area occupied by melanin granules has been taken as the melanin content index (MCI). There was a significantly different MCI between different skin types for bolh exposed (P<0.0001) and unexposed (P<0.0001) areas using the Kruskal-Wallis one-way ANOVA test. There was also a positive significant correlation between MCI and skin types II-VI in both exposed (r = 0.95, P< 0.00l) and unexposed areas (r = 0.89, P< 0.005). Image analysis also demonstrated that the number of melanin granules in surface corneocytes was significantly higher in the exposed area compared with the unexposed area, for skin types II, III, IV, V and VI. Melanin cap-like structures were also observed in exposed corneocytes and heavily pigmented skin contained larger melanin particles than fairer skin. The results indicate that an individual's skin phototype and melanin content, assessed by image analysis, have a significant correlation.     

Investigation of germinative cells in generating and renewed anagen hair apparatus in mice using anti-bromodeoxyuridine monoclonal antibody.

To elucidate the cell kinetics in generating and renewed anagen hair apparatus in mice, S-phase cells in dorsal skin of new-born and 14 to 25-day-old mice were labeled with bromodeoxyuridine (BrdU) and stained immunohistochemically using anti-BrdU monoclonal antibody. In primary hair germ, lower and outer cells were positively stained. In hair peg, the positive cells were divided into upper and lower portions. In bulbous hair peg, the lower positive cells gathered at the suprapapillary area, whereas the upper positive cells were located in the outer part of the hair apparatus. The latter positive cells were further divided in the middle and upper parts of the epithelial cord. The upper cells were going to form a sebaceous gland. From the suprapapillary group of germinative cells, hair cortex through the innermost cell layer of the outer root sheath were considered to be produced. The positive cells of the outer middle group may be important for elongation of hair apparatus and produce outer root sheath cells. At the end of anagen phase, first the suprapapillary cells became negative and then the outer root sheath cells became negative. BrdU-positive cells reappeared at the bottom of telogen hair apparatus and formed a secondary hair germ. Then, a similar cell kinetics was repeated in the renewed anagen hair apparatus. The germinative cells were separated into a few groups during the generation and cyclic changes of hair apparatus. Each cell group formed the individual part of the hair apparatus in a coordinate fashion, resulting in dynamic changes of the hair apparatus.