Ber-EP4 antigen is a marker for a cell population related to the secondary hair germ

Ber-EP4 is an antibody to a cell membrane glycoprotein of unknown function. In the skin, Ber-EP4 immunoreactivity has been reported to be localized in structures composed of basaloid epithelial cells, i.e. fetal epithelial germ cells, basal cell carcinoma, and trichoepithelioma as well as eccrine or apocrine ducts. In this study, we further characterized the follicular expression of Ber-EP4 immunoreactivity at different stages of the hair cycle of human terminal hair follicles. In addition, to clarify the location of Ber-EP4(+) cells, we compared the Ber-EP4 immunoreactivity with the expression of keratin 15 and keratin 19. Positive staining by Ber-EP4 was found in the lower part of the epithelial strand of late catagen hair follicles, in the secondary hair germ of telogen hair follicles, and in the matrix of early anagen hair follicles but not in any parts of mature anagen hair follicles. In contrast, the follicular expression of keratin 15 detected by using LHK15 antibody was restricted to two distinct parts of anagen hair follicles, i.e. the outer root sheath above the hair bulb and that of the isthmus including the bulge area, and to the outer root sheath of late catagen and telogen hair follicles. The follicular expressions of keratin 19 and that of keratin 15 were apparently superimposed, whereas keratin 15 expression was more extended. The immunoreactivity of LHK15 antibody and antikeratin 19 antibody against the secondary hair germ of telogen follicles was negative or dim. Our results suggest that Ber-EP4 reacts with the secondary hair germ and possibly a cell population related to the secondary hair germ but not with the presumptive stem cell population as revealed immunohistochemically either by the keratin 15 or keratin 19 expression.     

Trichogenic trichoblastoma arising on the supraclavicular fossa with an immunohistochemical study of cytokeratin expression

We report a 52-year-old female with trichogenic trichoblastoma arising on the supraclavicular fossa. Clinical and histological examinations revealed a thumbnail sized, elastic, hard, subcutaneous nodule which consisted of keratinous cysts and epithelial cords of basaloid cells with locally follicular differentiation. Based on histological observations, a diagnosis of trichogenic trichoblastoma was made. An immunohistochemical study using a panel of monoclonal antibodies against cytokeratins was performed to investigate the nature and differentiation of this tumour. The most characteristic findings of the immunohistochemistry were CK 8 and 19 expression in the epithelial cords and the outer cells of the cystic structures. These immunoreactivities were similar to those of the outermost layer of the outer root sheath between the lower permanent portion and the upper transient portion, and immunostaining with the other antibodies confirmed this similarity. We can speculate that trichogenic trichoblastoma differentiates mainly toward the outermost layer of the outer root sheath between the lower permanent portion and the upper transient portion, and then into follicular structures.     

Tricholemmal carcinoma in continuity with trichoblastoma within nevus sebaceus

A nodule arising within the nevus sebaceus on the vertex of the scalp of a 68-year-old woman was histopathologically and immunohistochemically investigated. We also used immunohistochemistry to investigate the cytokeratin (CK) distribution of the outer root sheaths of normal terminal hair follicles. The nodule consisted of two parts, a main exophytic part with a lobular proliferation and a small peripheral part with the features of trichoblastoma. The main exophytic lesion consisted of lobular aggregations composed of both or either basaloid cells and clear cells with the silhouette and cytology of malignancy. The columnar clear cells were aligned in a palisade at the periphery of the aggregations of clear cells, and the aggregations located in the superficial dermis were connected to the follicular infundibular structures. Almost all of the neoplastic aggregations were diffusely positive for CK7 (OV/TLR/30), and the innermost or inner cells of the neoplastic aggregations were positive for CK17; a similar staining pattern to that in the lower portion of the outer root sheath between the A and B fringes in normal terminal hair follicles. The exophytic part of the lesion was a malignant neoplasm with differentiation mainly toward the lower segment of the outer sheath between the A and B fringes of the terminal hair follicle, namely tricholemmal carcinoma. Our case may represent a collision of two distinctive neoplasms (tricholemmal carcinoma and trichoblastoma), however, an intimate relationship between these two neoplasms also should be considered.     

Immunohistochemical and ultrastructural observations of desmoplastic trichoepithelioma with a special reference to a morphological comparison with normal apocrine acrosyringeum

BACKGROUND: Desmoplastic trichoepithelioma is a benign neoplasm considered to have follicular differentiation. Its sweat gland- or sebaceous-lines of differentiation have been also reported. There have been, however, only a few reports regarding extensive immunohistochemical and ultrastructural investigations of this neoplasm. METHODS: Histopathological and immunohistochemical studies were performed on three cases of desmoplastic trichoepithelioma, comparing it with normal skin. One of these cases was ultrastructurally investigated. RESULTS: The cord-like basaloid nests were reacted with the anti-cytokeratin (CK)1/5/10/14, -CK5/8, -CK14 and -CK15 antibodies, but not with the anti-CK6 antibody. Similar findings were observed in the outer layers of the normal follicular outer root sheath. Basaloid cell nests in one case, which showed ductal structures in the nests, also expressed CK7, CK8/18 and CK19. These keratins were also detected in the normal sweat glands. In addition, CK8/18 and CK19 were expressed in the basal cells of the outer root sheath. Keratinous cysts had inner reactions with the anti-CK10/11 and -CK6 antibodies, and outer reactions with anti-CK5/8 and -CK14 antibodies. Ultrastructurally, the cells in the cord-like nests were basically immature and basaloid in appearance. A few cells contained Odland bodies, which were also observed in the normal apocrine acrosyringeum. The ductal structure was lined by the cells which bore numerous microvilli in the luminal surface. CONCLUSION: The cells in desmoplastic trichoepithelioma are suggested to be in close association with the basal cells in the outer root sheath, which can differentiate into various parts of the folliculosebaceous apocrine unit.     

Accordion-like Structure of Terminal Hair Follicles of the Human Scalp

Terminal hair follicles extracted after ethylenediaminetetraacetic acid treatment preserved the basal cell surface of the outer root sheath well enough to examine the outer surface in detail. Light microscopic observations of whole mount specimens revealed several sawtooth-like structures of follicular epithelium in the lower portion of terminal hair follicle. Vertical sections of the human scalp also showed several invaginations of the outer root sheath of terminal hair follicles in the lower portion, not in association with the arrector pili muscle. Scanning electron microscopy of the same specimens demonstrated accordion-like structures below the sebaceous gland in the lower half of anagen terminal hair follicles and surrounding the entire circumference of the follicles. Sawtooth-like structures were unilaterally observed at the level of the middle or lower portion below the sebaceous gland. With transmission electron microscopy, these structures were seen as undulations of basal cells which preserved hemidesmosomes, although the basal lamina had been peeled off during the extraction procedure. Thus, this accordion-like structure is a genuine structural variation of some human anagen hair follicles and not an artifact.     

Expression of Lewis Y (Ley) Antigen in Human Anagen Hair Follicles

Lewis Y (Le^y) antigen, a difucosylated tetrasaccharide found on type 2 blood group oligosaccharides of glycolipids and glycoproteins, is thought to be a phenotypic marker predictive of cell differentiation. The distribution of this antigen in human anagen hair follicles was examined by immunohistochemical staining using a monoclonal antibody (AH-6) to Le^y. In the bulbar and suprabulbar portion of anagen hair follicles, Le^y antigen was detected in the three layers of the inner root sheath. Subsequently, the positive staining became translocated to the innermost layer of the outer root sheath in the middle part of the hair follicles. In the upper portion of the hair follicles, Le^y antigen was found in the outer cells of the outer root sheath. These findings suggested that the expression of Le^y antigen in the anagen hair follicles was correlated with the processes of keratinization or terminal differentiation.     

Case of follicular mucinosis: Nestin-expression in mucin-producing cells

A 29-year-old Japanese man had an asymptomatic, solitary, indurated, erythematous plaque measuring 30 mm × 30 mm on his jaw that had been present for a month. The skin lesion had follicular hyperkeratosis, and lacked hair. A skin biopsy specimen showed a dense perifollicular infiltration composed of lymphocytes, with an admixture of eosinophils in the full thickness of the dermis. The hair follicles and sebaceous glands had reticular epithelial degeneration by mucoid material of the outer root sheath and sebaceous epithelium. The mucoid material stained with Alcian blue at pH 2.5. The clinical and histological features were consistent with the diagnosis of follicular mucinosis. On immunohistochemistry, the outer root sheath cells with reticular epithelial degeneration were nestin-positive and keratin 15-negative. These results suggest that the outer root sheath cells with reticular epithelial degeneration come from the nestin-positive, multipotent, hair follicle stem cells.     

p75 Neurotrophin receptor differentiates between morphoeic basal cell carcinoma and desmoplastic trichoepithelioma: insights into the histogenesis of adnexal tumours based on embryology and hair follicle biology

Background Tumour development is frequently described in the basic pathology literature as a recapitulation of embryogenesis. However, a link between the embryology of the skin and the histogenesis of adnexal tumours has been largely overlooked. The low‐affinity p75 neurotrophin receptor (p75NTR) has a profound role in hair follicle biology. We therefore speculated that it is involved in the histogenesis of follicular adnexal tumours. One of the most challenging diagnoses in dermatopathology is differentiating morphoeic basal cell carcinoma from desmoplastic trichoepithelioma. Objectives To describe the expression pattern of p75NTR during cutaneous embryogenesis, in the adult hair follicle and in morphoeic basal cell carcinoma and desmoplastic trichoepithelioma. Methods Evaluation of the staining pattern for p75NTR was performed using standard immunohistochemical techniques. For comparison, we examined staining for cytokeratin 20 which highlights Merkel cells. Results All 17 desmoplastic trichoepitheliomas were immunoreactive with > 80% of the cells stained, whereas 12 of the 14 (86%) morphoeic basal cell carcinomas were p75NTR negative. In the two positive cases of morphoeic basal cell carcinoma < 30% of cells were labelled. In the late bulbous hair peg stage and in the postnatal anagen hair follicle p75NTR highlights the outer root sheath. Conclusions Our results support the classification of desmoplastic trichoepithelioma as a follicular hamartoma mimicking the outer root sheath. In contrast, the lack of p75NTR expression in morphoeic basal cell carcinoma favours a concept of this tumour as a more primitive follicular lesion with the characteristics of a carcinoma and not a hamartoma. We suggest including p75NTR as a tool in the differential diagnosis between morphoeic basal cell carcinoma and desmoplastic trichoepithelioma.     

Co-culture of human hair follicles and dermal papillae in a collagen matrix

Human hair follicles, either alone or in combination with dermal papillae, were cultured in a collagen matrix. When plucked hair follicles were cultured alone, spike-like structures composed of outer root sheath cells started growing around the follicle and then radiated into the gel. When isolated dermal papillae were embedded close to the follicles, spikes started growing earlier and grew more rapidly than without the papillae. In cultures of excised follicles from which the dermal papilla had been removed, epithelial cells (possibly hair bulb cells) started growing out from the bulbous portion and then also formed spikes. In the presence of a papilla, the spikes elongated toward the papilla, finally reaching and surrounding it. These findings suggest that dermal papilla cells produce a factor(s) that enhances growth of follicular epithelial cells and also attracts those cells. In cultures of whole excised follicles, two major characteristic patterns of cellular growth were recognized. When the dermal papilla remained inside the bulb in contact with the hair bulb matrix, the hair matrix cells proliferated and differentiated in the normal manner, resulting in elongation of the hair shaft and follicle. But when the papilla was detached from the hair bulb matrix, epithelial cells proliferated from the bulbous portion and finally formed hair follicle-like structures. Thus, attachment of the dermal papilla to the hair bulb matrix in the bulbous portion appears to be necessary for growth of the hair and follicle in the normal manner. Our model may be useful for examining the interaction between follicular epithelial cells and dermal papillae and for studying the growth of hair and follicles in vitro.     

The nevoid pili multigemini over the back

Pili multigemini is a rare developmental defect of hair follicles. It usually involves the beard of an adult and the scalp in children, but there have been no reported cases on the back. We report 3 cases of extensive pili multigemini over the entire back of healthy males. All cases were found incidentally. The direct microscopic examination of one hair follicle showed that it consisted of more than twenty shafts, which had rough surfaces and brush-like bulbs. The histological examination revealed that complicated follicular structures formed as many as 23 to even 36 hair shafts. Lots of hairs were surrounded by each inner root sheath and had one common outer root sheath. We suggest this nevoid is pili multigemini over the back.     

Immunohistochemical study of angiotensin receptors in human anagen hair follicles and basal cell carcinoma

BACKGROUND: Angiotensin receptors are the specific receptors of angiotensin II of the renin-angiotensin system. However, expression of the receptors in hair follicles has not been determined. OBJECTS: To clarify the expression and localization of angiotensin receptors in human anagen hair follicles and basal cell carcinomas. METHODS: We studied immunohistochemically the expression of angiotensin type 1(AT1) and type 2 (AT2) receptors in human anagen hair follicles and in 16 cases of basal cell carcinoma (BCC) (nine of solid BCC of the circumscribed type, two of adenoid BCC, five of BCC with follicular differentiation). RESULTS: Our experiments demonstrated the localization of AT1 in the inner root sheath and the inner layers of the outer root sheath. In BCC, positive staining with AT1 was revealed in the tumour cells of basal cell carcinoma with follicular differentiation. CONCLUSIONS: AT1 may have a role in association with follicular keratinization. Studying AT1 distribution may be useful in understanding the pathophysiology of human hair follicles and the hair follicle-associated tumours.     

Immunohistochemical localization of cytokeratins and involucrin in calcifying epithelioma: comparative studies with normal skin

The expression of cytokeratins and involucrin varies greatly in different epithelia, and this raises the possibility that detailed analysis of these epidermal proteins might provide a means of identifying various skin tumours. The present study was conducted to determine the immunohistochemical distribution of cytokeratins and involucrin in calcifying epithelioma of Malherbe, in order to elucidate the nature and differentiation of this tumour. To correlate the immunohistochemical profile with the most frequest histological patterns, we categorized the basophilic, transitional, shadow, and squamoid cells, and the shreds of keratin. Comparative studies with normal skin showed that the shadow and transitional cells corresponded to hair cortex cells, the squamoid cells to the outer root sheath, the basophilic cells adjacent to the stroma to the outermost cell layer of the outer root sheath between the lower permanent portion and upper transient portion of the follicles, and the basophilic cells adjacent to the transitional cells to the hair matrix. The expression of cytokeratins in most shreds of keratin was similar to that in squamoid cells. Calcifying epithelioma was, therefore, shown to be composed of tumour cells differentiating into both the hair cortex and outer root sheath. These tumour cells were differentiated from basophilic cells, which showed the same staining patterns as the outermost cell layer of the outer root sheath between the lower permanent portion and upper transient portion of the hair follicles, supporting the hypothesis that the keratinocytes in the outermost cell layer can differentiate into the transitional portion of the follicle and anagen hair.     

Immunohistochemical study of calretinin in normal skin and cutaneous adnexal proliferations

Calretinin is a calcium-binding protein member of the EF-hand family. The presence of calretinin has been demonstrated in certain stages of the cellular cycle in a wide variety of normal and neoplastic tissues. The main aims of our study were (1) to investigate what structures of the normal skin and cutaneous adnexal proliferations express immunoreactivity for calretinin and (2) to determine the value of immunohistochemical expression for calretinin as a marker for follicular, sebaceous, apocrine, and eccrine differentiation in cutaneous adnexal proliferations. We studied 139 biopsy specimens, including 10 cases of normal skin of different locations and 129 benign and malignant cutaneous adnexal proliferations. In normal skin, we found that calretinin is expressed in the innermost cell layer of the outer root sheath in anagen hair follicle, in both the duct and sebolemma of the sebaceous gland, in the secretory portion of eccrine glands, and in mast cells of the stroma. In cutaneous adnexal proliferations, we found strong immunoreactivity for calretinin in tricholemmal cysts, tricholemmomas/inverted follicular keratoses, tumors of follicular infundibulum, and in some basal cell carcinomas. Focal positivity was also seen in trichoadenomas, trichoblastomas/trichoepitheliomas, pilomatricomas, proliferating tricholemmal tumors, pilar sheath acanthomas, trichofolliculomas, follicular hybrid cysts, cutaneous mixed tumors, steatocystomas, sebaceous hyperplasias, and sebaceomas. These results demonstrate that immunohistochemical study for calretinin may be helpful to identify the innermost cell layer of the outer root sheath in anagen hair follicle and the cutaneous adnexal proliferations showing differentiation toward this structure. Calretinin immunoreactivity supports eccrine differentiation in some sweat gland neoplasms, and it is also useful in identifying neoplasms with ductal sebaceous differentiation.     

Giant solitary trichoepithelioma

The giant solitary trichoepithelioma is a rare trichogenic tumor with potential for local recurrence. Only nine cases have been previously described in the literature, and one additional case without recurrence during the first 3.5 years of observation is presented stressing that the rate of recurrence is low.     

Immunohistochemical study of calretinin in normal hair follicles and tumors with follicular differentiation

BackgroundSelective immunostaining for calretinin labels the innermost layer of the outer root sheath of normal hair follicles, which is difficult to distinguish with hematoxylin-eosin staining.ObjectiveThe aim of this study was to determine whether immunohistochemistry for calretinin allows identification of cutaneous adnexal tumors with follicular differentiation towards cells of the outer root sheath.Material and methodsWe analyzed the staining pattern for calretinin by immunohistochemistry in 49 biopsies of cutaneous adnexal tumors with follicular differentiation.ResultsFifteen biopsies corresponded to trichilemmomas/inverted follicular keratosis and had staining for calretinin in the epithelium of the most superficial areas of the lesions and in squamous eddies. Ten were trichilemmal cysts, which displayed staining of the cyst wall. Three were basal cell carcinomas with variable staining according to the type of follicular differentiation in each variant. One was a panfolliculoma that had focal staining. Two were folliculosebaceous cystic hamartomas with staining of the excretory duct of the sebaceous glands. Two pilomatricomas and 3 proliferative trichilemmal tumors had positive staining in the cellular layers close to the lumen of the cystic structures. Nine trichoblastomas/trichoepitheliomas, 2 infundibular cysts, 1 dilated pore of Winer, and 2 acanthomas of the follicular sheath were negative for calretinin.ConclusionImmunohistochemistry for calretinin allows identification of cutaneous adnexal tumors of the hair follicle or a component of the follicle with differentiation towards cells of the outer root sheath.     

嗜酸性粒细胞性脓疱性毛囊炎1例

嗜酸性粒细胞性脓疱性毛囊炎（EPF）在国内较少报告。本文报告1例EPF。患者男,32岁,右眉弓上方红斑伴瘙痒3个月,病理切片显示：大量嗜酸性粒细胞侵入毛囊外毛根鞘部,形成脓肿。真皮上部也有较多嗜酸性粒细胞,为较典型的经典型EPF。     

Trichoblastic fibroma. A clinicopathologic study of three cases

Three cases of trichoblastic fibroma, a rare benign skin tumor of hair follicle origin, are reported. On clinical examination, solitary, mobile, subcutaneous nodules with normal overlying skin were found on the vulva (one case) and scalp (two cases) in women aged 57, 46, and 19 years, respectively. On microscopic examination, the tumors were composed of complex nests and strands of basaloid, focally keratinized epithelium arranged in a moderately cellular fibroblastic stroma. No connection with the overlying epithelium or adjacent adnexal structures was observed. Immunohistochemical staining supported a trichogenic origin for these tumors. Trichoblastic fibromas are histologically distinctive lesions that should be distinguished from other tumors of follicular origin and from keratotic basal cell carcinoma.     

毛胚瘤一例

国内首次报道一例良性毛囊性肿瘤——毛胚瘤.患者男,48岁,前胸壁无症状皮下结节10年.组织学显示肿瘤位于真皮,境界清楚,边缘有纤维性假包膜,瘤团由结节和囊肿构成,大多数结节显示中央透明细胞呈同心圆分布,周围嗜碱性细胞呈栅栏状排列.可见肿瘤向毛球、内毛根鞘、外毛根鞘和毛囊漏斗部分化.免疫组化显示,肿瘤细胞表达角蛋白AE1/AE3、CK5/6和CK17,不表达CK7或CK20.中央透明细胞和周边栅栏状细胞显示完全不同的免疫组化表达方式.结合组织学和免疫组化改变诊断毛胚瘤.     

Nevoid bundle hairs

We report on two cases of naevoid bundle hair of the scalp. The clinical picture is characterized by an abnormal grouping of hairs emerging from one follicle ostium. The hairs arise from separate follicles but fuse into a common outer hair root sheath in the above the sebaceous gland. The outer hair root sheath is characterized by its abnormal reactivity with monoclonal antibodies against keratin but normal reactivity with anti-filaggrin. Naevoid bundle hair is thought to be an atavistic hair growth pattern.     

The innermost cells of the outer root sheath in human anagen hair follicles undergo specialized keratinization mediated by apoptosis

The innermost cell layer of the outer root sheath (IORS) is a special single cell layer located just outside Henle's layer. In situ endlabeling immunohistochemistry for apoptosis showed that labeled cells were most consistently located in the IORS from the suprabulbar portion to the infundibulum of anagen terminal hair follicles of the human scalp. Labeled cells were also sparsely scattered in the middle portion, including the bulge area of the outer root sheath of anagen hair, the regressing lower portion of catagen hair and the bulb of telogen hair. Ultrastructurally, the cells of the innermost layer underwent cellular degeneration through cytoplasmic vacuolization and nuclear pyknosis without keratohyalin production. These were compatible with the morphology of apoptotic cells. These findings confirmed that the innermost cell layer is different from other layers of the outer root sheath, not only by previously demonstrated criteria such as Ki67 immunostainability and characteristic ultrastructure but also by the mode of cell death.