Profiling the human hair follicle immune system in lichen planopilaris and frontal fibrosing alopecia: can macrophage polarization differentiate these two conditions microscopically?

BACKGROUND: Frontal fibrosing alopecia (FFA) is traditionally regarded as a variant of lichen planopilaris (LPP) based on histological features. Distinct clinical presentation, demographics and epidemiology suggest that differing pathogenic factors determine the final phenotype. OBJECTIVES: To map the hair follicle immune system in LPP and FFA by systematically comparing key inflammatory markers in defined hair follicle compartments. METHODS: Lesional scalp biopsies from LPP and FFA and healthy controls were stained with the following immunohistochemical markers: CD1a and CD209, CD4, CD8, CD56, CD68, CD123, CXCR3, forkhead box (FOX)P3, mast cell tryptase and cKit. Macrophage polarization was explored using CD206, CD163, CD86, receptor for advanced glycation end products (RAGE), interleukin (IL)-4 and IL-13 on paired lesional and nonlesional LPP and FFA samples. RESULTS: Increased numbers of CD8+ , CXCR3+ and FOXP3+ T cells and CD68+ macrophages were identified in the distal hair follicle epithelium and perifollicular mesenchyme in both LPP and FFA compared with controls. In both LPP and FFA, total and degranulated mast cells and CD123+ plasmacytoid dendritic cells were increased in the perifollicular mesenchyme adjacent to the bulge and infundibulum, whereas numbers of CD1a+ and CD209+ dendritic cells were significantly reduced in the infundibulum connective tissue sheath. However, only with CD68 staining was a significant difference between LPP and FFA identified, with greater numbers of CD68+ cells in LPP samples. Furthermore, the identified macrophage polarization markers downregulated CD86 and upregulated CD163 and IL-4 expression in lesional LPP compared with FFA samples. CONCLUSIONS: This comparative immunopathological analysis is the first to profile systematically the hair follicle immune system in LPP and FFA. Our analysis highlights a potential role of macrophages in disease pathobiology and suggests that macrophage polarization may differ between LPP and FFA, allowing microscopic differentiation. Linked Comment: Kinoshita-Ise. Br J Dermatol 2020; 183:419-420.

Eccrine sweat glands associate with the human hair follicle within a defined compartment of dermal white adipose tissue.

BACKGROUND: Eccrine sweat glands (ESGs) are critical for thermoregulation and are involved in wound healing. ESGs have traditionally been considered as separate skin appendages without connection to the pilosebaceous unit (PSU). However, recent preliminary evidence has encouraged the hypothesis that the PSU and ESG are more interconnected than previously thought. OBJECTIVES: To re-evaluate the morphology of human skin adnexa with an integrated three-dimensional (3D) perspective in order to explore the possible interconnections that the PSU and the ESG may form. METHODS: A systematic 3D reconstruction method of skin sections, direct visualization of human scalp follicular unit transplant grafts and a scalp strip ex vivo were used to validate and further explore the hypothesis. RESULTS: We demonstrate that the coiled portion of most ESGs is morphologically integrated into the PSU of human scalp skin and forms a structural unit that is embedded into a specific, hair follicle-associated region of dermal white adipose tissue (dWAT). This newly recognized unit is easily accessible and experimentally tractable by organ culture of follicular units and can be visualized intravitally. CONCLUSIONS: We propose a model of functional human skin anatomy in which ESGs are closely associated with the PSU and the dWAT to form a common homeostatic tissue environment, which may best be encapsulated in the term 'adnexal skin unit'. The challenge now is to dissect how each component of this superstructure of human skin functionally cooperates with and influences the other under physiological conditions, during regeneration and repair and in selected skin diseases.

Biology of the eyelash hair follicle: an enigma in plain sight.

Because of their crucial impact on our perception of beauty, eyelashes constitute a prime target for the cosmetic industry. However, when compared with other hair shafts and the mini-organs that produce them [eyelash hair follicles (ELHFs)], knowledge on the biology underlying growth and pigmentation of eyelashes is still rudimentary. This is due in part to the extremely restricted availability of human ELHFs for experimental study, underappreciation of their important sensory and protective functions and insufficient interest in understanding why they are distinct from scalp hair follicles (HFs) (e.g. ELHFs produce shorter hair shafts, do not possess an arrector pili muscle, have a shorter hair cycle and undergo greying significantly later than scalp HFs). Here we synthesize the limited current knowledge on the biology of ELHFs, in humans and other species, their role in health and disease, the known similarities with and differences from other HF populations, and their intrinsic interethnic variations. We define major open questions in the biology of these intriguing mini-organs and conclude by proposing future research directions. These include dissecting the molecular and cellular mechanisms that underlie trichomegaly and the development of in vitro models in order to interrogate the distinct molecular controls of ELHF growth, cycling and pigmentation and to probe novel strategies for the therapeutic and cosmetic manipulation of ELHFs beyond prostaglandin receptor stimulation.

CD10 and CD34 in fetal and adult human hair follicles: dynamic changes in their immunohistochemical expression during embryogenesis and hair cycling.

BACKGROUND: CD10 and CD34 have been detected in both epithelial and mesenchymal components of anagen human hair follicles. OBJECTIVES: To analyse the expression of CD10 and CD34 in human hair follicle development as well as in different phases of the hair cycle. METHODS: Fetal and adult hair follicles at different stages of the hair cycle were examined by immunohistochemistry for CD10 and CD34. RESULTS: In fetal follicles, CD10 is expressed by the cells of the placodes, and CD34 by the mesenchymal cells of the dermal condensate. As the follicle matures, CD10 can be seen in the matrix cells, inner root sheath and dermal sheath. In adult follicles, the expression of CD10 in the follicular epithelium is present in anagen follicles, but tends to disappear in catagen, and is not detected in telogen. The CD10 positivity of the dermal sheath is more intense in catagen than in anagen follicles. CD34 immunostaining of the external root sheath was seen in adult anagen follicles but not in fetal follicles. This staining of the anagen outer sheath tends to disappear in catagen and is not detected in telogen. CONCLUSIONS: CD10 and CD34 are not proteins constantly present in a specific cell type of the hair follicle, but are proteins that can be expressed by both epithelial and mesenchymal cells depending on the stage of development and hair cycle. The distribution of the immunoreactivity to CD10 in the placode and CD34 in the dermal condensate suggests a role of these proteins in initial stages of hair formation.

Sarcomatoid basal cell carcinoma--predilection for osteosarcomatous differentiation: a series of 11 cases.

Primary cutaneous carcinomas rarely show heterologous malignant mesenchymal differentiation. We report 11 cases of sarcomatoid basal cell carcinoma (BCC) with osteosarcomatous differentiation. The patients (7 men and 4 women) ranged in age from 61 to 92 years (median 75 y). The tumors presented as exophytic nodules (0.3 to 7 cm) on the head (n=6), upper limb (n=3), and lower limb (n=2). All lesions were completely excised. Seven patients were alive without evidence of disease (follow-up interval 5 to 24 mo) and 1 patient died of unrelated causes at 7 months without evidence of disease. On histology, the tumors were dermal in location with 2 cases showing focal subcutaneous involvement. Ten tumors were well-circumscribed and 1 tumor showed focally infiltrative edges. Ten tumors revealed conventional BCC associated with varying proportions of osteosarcomatous and undifferentiated sarcomatous stroma. Transition from neoplastic epithelial to mesenchymal cells was seen in 8 cases. One case showed a purely osteoclastic giant cell rich malignant mesenchyme, interpreted as representing early stages of osteosarcomatous transformation. Previously unreported in sarcomatoid BCC, the mesenchymal component of another two cases displayed predominant malignant giant cell tumor like areas and 1 further case disclosed areas reminiscent of telangiectatic osteosarcoma. Pancytokeratins (AE1/3 and MNF116) and smooth muscle actin stained occasional undifferentiated sarcomatous cells in 2 and 3 tumors, respectively. MNF116 and EMA were focally positive in osteosarcomatous tumor cells of 1 case. Although the follow-up interval is short, our data suggest an excellent prognosis for polypoid and exophytic sarcomatoid BCC after complete surgical resection.

Human papillomavirus-associated penile squamous cell carcinoma in HIV-positive patients.

Two cases of penile squamous cell carcinoma with distinctive clinicopathologic characteristics are presented. The tumors appeared in patients infected with HIV and were located in the glans of the penis. Histologically, the neoplasms were well-differentiated, infiltrating, squamous cell carcinomas. The entire spectrum from benign condyloma to infiltrative squamous cell carcinoma was present in the two patients. In both cases, human papillomavirus (HPV) could be demonstrated using polymerase chain reaction analysis. The reported cases suggest a synergic interaction of HPV and HIV in the carcinogenic process of some penile carcinomas.

Different immunoreactivity of endothelial markers in well and poorly differentiated areas of angiosarcomas.

This study evaluated the immunohistochemical staining of four endothelial cell markers in well differentiated and poorly differentiated areas of angiosarcomas. Formaldehyde-fixed, paraffin-embedded sections from eight angiosarcomas were studied using the antibodies anti-factor VIII-related antigen (FVIII-RA), Ulex europaeus I agglutinin, anti-CD34 (QBEND/10) and anti-CD31 (JC70). The immunostaining of the angiomatous (well differentiated) and solid (poorly differentiated) areas was separately analysed and specificity was evaluated in 20 non-vascular tumours. The antibody anti-CD31 and Ulex europaeus were the most sensitive markers staining well differentiated vasoformative structures and poorly differentiated solid areas. Anti-FVIII-RA and anti-CD34 did not stain undifferentiated malignant endothelial cells from solid areas. Ulex europueus and anti-CD34 showed very low specificity; in contrast, none of the non-vascular tumours expressed CD31 or FVIII-RA. JC70 (anti-CD31) appears to be the most useful marker in elucidating the vascular nature of angiosarcomas. Is important to emphasize the lack of specificity of Ulex europaeus and the low sensitivity of anti-CD34 and anti-FVIII-RA for poorly differentiated lesions.

Prostatic carcinosarcoma: a case originating in a previous ductal adenocarcinoma of the prostate.

Ductal adenocarcinoma of the prostate is a variant of prostatic carcinoma that appears to originate in the ducts of the prostate. Carcinosarcoma of the prostate is an uncommon and aggressive tumour composed of an intimate admixture of adenocarcinoma and sarcoma. In this report we describe the clinicopathological and immunohistochemical characteristics of a case of prostatic carcinosarcoma that appeared in a 66-year-old man who had had a ductal adenocarcinoma of the prostate diagnosed 3 years previously. The patient died of the disease 3 months after the carcinosarcoma was diagnosed. This case may represent further evidence of the dedifferentiation theory in the origin of carcinosarcoma. The case also illustrates that this dedifferentiation may occur from any type of prostatic carcinoma.

Exuberant granulation tissue mimicking vascular tumours associated with burns.

A case of simultaneous development of multiple vascular neoplasms in a patient with a previous history of burns and lymphoblastic lymphoma is reported. Microscopic examination revealed angiomatosis made up of diffuse capillary proliferation. We speculate that endogenous factors could have played an important role in the development of these neoplasms. We discuss the clinical and histological differential diagnosis of the case presented: a disseminated variant of lobular capillary haemangioma, Kaposi's sarcoma, bacillary angiomatosis and hyperplastic granulation tissue.

Epithelial-myoepithelial carcinoma of the salivary gland. Fine needle aspiration cytologic findings.

A case of epithelial-myoepithelial carcinoma of the salivary gland in a 78-year-old patient is presented. Fine needle aspiration cytologic smears showed a moderate number of tumor cells arranged in three-dimensional, well-outlined clusters reminiscent of the ball-like structures of adenoid cystic carcinoma. The nuclei were small and monotonous, with finely granular chromatin and small nucleoli. A large number of cells showed abundant clear cytoplasm; however, in some of the clusters the cytoplasms were very scant, again mimicking adenoid cystic carcinoma. Fragments of pale homogeneous acellular material, isolated or surrounding the cellular clusters, were another conspicuous finding.

[Primary amyloidosis associated to severe factor X deficiency]. / Amiloidosis primaria (AL) asociada a déficit severo de factor X.

Amyloidosis is a systemic disease characterized by generalized deposition of beta-organized proteic fibrillar material with green birefringence under polarized light, in different tissues and organs, the most frequent kidney, liver and heart, with important clinical repercussion. Primary or AL amyloidosis is the most common subtype of amyloidosis (1), confirmed by biopsy-proved amyloid deposition in abdominal fat pad, rectum, kidney or liver, if necessary, in which fragments of monoclonal light chains are deposited. Cases with factor X (Stuart factor) of coagulation deficiency associated are described, due to adsorption of this factor to amyloid fibrills. Normally, evolution is fatal, with only few months of survival. We report a case of primary amyloidosis with nephrotic syndrome, severe factor X deficiency (without bleeding complications), possible heart affection and short-term good response to chemotherapic treatment.

Human papillomavirus in carcinomas of the tongue: clinical and prognostic implications.

It is not clear whether the presence of human papillomavirus (HPV) in squamous cell carcinomas of the tongue (SCCT) is of etiopathogenic and clinical significance. This study was designed to establish the incidence of HPV in SCCT and to determine the influence of HPV detection on clinical parameters and the prognosis. Clinical and histopathological data of 64 patients with SCCT were collected. Thirty benign lesions of the tongue were analyzed in parallel, in order to compare the HPV incidence and genotypes in these lesions with those of SCCT. Paraffin blocks of all cases were collected and PCR was carried out using SPF10 primers and the INNO-LiPA genotyping methodology. HPV was detected in 26.2% of the patients. Hybridization results showed that all patients except one had high-risk (HR)-HPV. HPV56 was the most common (42.1%), followed by HPV18 (26.3%), HPV16 (10.5%), HPV66 (10.5%), HPV39 (5.3%), and HPV51 (5.3%). The odds ratio of HR-HPV infection in cases vs. controls was statistically significant (9.45, 95% confidence interval 1.18-75.46). Among the results of the univariate analysis correlating the presence of HR-HPV with different clinical parameters, only mortality showed a statistically significant correlation, being higher in HR-HPV patients (odds ratio 3.97, 95% confidence interval 1.07-14.7).

CD133 expression in normal skin and in epithelial cutaneous tumors.

BACKGROUND: Expression of human CD133 (human prominin-1) in cancer cells has been postulated to be a marker of stemness and is considered as a putative marker of cancer stem cells (CSCs). We designed a study to describe the expression pattern of CD133 in normal skin and in epithelial cutaneous neoplasms. METHODS: The CD133 immunohistochemical expression of forty-three eccrine and apocrine tumors was compared to that observed in other epithelial tumors of the skin. In addition, flow cytometry was used to detect the CD133 expression of four epithelial skin neoplasms, including one porocarcinoma. RESULTS: CD133 immunoreactivity at the apical or at the apicolateral surface of cells forming glandular structures was observed. Cells from solid areas of benign or malignant tumors were not stained. The porocarcinoma derived culture cells showed a 22% of CD133 positive cells using flow cytometry, while squamous cell carcinoma cultures contained less than 0.1%. CONCLUSIONS: These observations indicate that CD133 is a specific marker of glandular differentiation that could be included in the diagnostic panel of cutaneous tumors with possible eccrine or apocrine differentiation. However, the use of CD133 expression as a marker of CSCs should be interpreted with caution in experiments of skin.

High prevalence of human papillomavirus 16 in penile carcinoma.

In order to analyze the incidence and prevalence of Human Papillomavirus (HPV) in penile carcinoma, we studied 49 patients with penile carcinoma. Formalin-fixed, paraffin-embedded tissue samples were collected from 64 samples of penile carcinoma from the Hospital General Universitario (Albacete, Spain). Cases were histologically classified and the polymerase chain reaction (PCR) method was used to detect the presence of HPV. Two sets of consensus primers were used, the My09/My11, and the GP5+/GP6+. All positive cases were sequenced in order to establish the implicated genotype. Our results showed that 38 of the 49 cases were positive for HPV (77,5%). HPV16 appeared in 32 (84,2 %) of the 38 positive cases and HPV18 in 4 (10,5%). Our data demonstrate that the My09/My11 primers are more sensitive than GP5+/GP6+ primers, although the combination of the two sets of primers notably increased the total number of HPV positive cases detected.

The immunohistochemical expression of CD34 in human hair follicles: a comparative study with the bulge marker CK15.

BACKGROUND: Anti-CD34 antibodies label the bulge region of mouse hair follicles. However, in human hair follicles, CD34 immunoreactivity is found in the outer root sheath below the bulge zone. The immunohistochemical staining of CD34 in catagen and telogen follicles has not been evaluated. AIMS: To characterize the expression of CD34 immunoreactivity at different stages of the hair cycle in human terminal hair follicles, and to compare the immunostaining pattern of CD34 with that of CK15, used here as a marker of the bulge region. METHOD: Serial vertical sections of human hair follicles in anagen, catagen and telogen phases were immunostained with anti-CD34 (QBEnd 10) and anti-CK15 (LHK15 and C8/144B) antibodies. Double-labelling immunofluorescence was also performed. RESULTS: The catagen and telogen follicles studied did not show CD34 immunoreactivity in the outer root sheath. The location of CD34 and CK15 immunoreactivity in anagen follicles reveals a different staining pattern: CD34-positive cells are located in the outer root sheath below the attachment zone of the arrector pili muscle, whereas CK15-positive cells are located in the outer root sheath above the attachment zone of the arrector pili muscle. CONCLUSIONS: Only anagen human hair follicles show CD34 immunoreactivity. CD34 and CK15 recognize different types of cells or cells at different stages of differentiation.

The calcium-binding protein calretinin is a marker of the companion cell layer of the human hair follicle.

BACKGROUND: Ultrastructural studies of the hair follicle show that the outer root sheath (ORS) does not consist of a homogeneous cell population. The innermost cell layer of the ORS, also called the companion layer, is a single cell layer closely associated with the Henle layer of the inner root sheath. OBJECTIVES: To describe the immunohistochemical expression of calretinin, a calcium-binding protein, in the human hair follicle. METHODS: Immunohistochemical studies using two different antisera to calretinin were performed in paraffin-embedded and in frozen scalp specimens using standard techniques. RESULTS: Calretinin immunostaining was consistently and specifically found in the companion cell layer of hair follicles. CONCLUSIONS: These findings provide further evidence to support the notion that the companion layer is not only morphologically, but also immunohistochemically, different from the other cells of the ORS.

QBEND/10 (anti-CD34 antibody) in external root sheath cells and follicular tumors.

The human hematopoietic progenitor cell antigen (CD34) is a cell surface protein expressed by human hematopoietic progenitor cells, vascular endothelium, and many mesenchymal tumors. Sections from six samples of normal skin and from 41 epithelial tumors of the skin were studied. Immunostaining of epithelial cells from the external root sheath below the attachment of the arrector pili muscle and above the matrix cells was noted in normal samples. Tumors derived from or differentiated toward cells of the outer sheath, especially trichilemmomas, were immunostained with QBEND/10 (anti-CD34 antibody), whereas other epithelial tumors studied were negative. CD34 could serve as a marker of outer sheath cell derivation and may well be of value in the distinction between trichilemmomas and other lesions with similar histopathological features.

Trichilemmal keratosis. A clinicopathologic and immunohistochemical study of two cases.

Trichilemmal keratosis (TK) is an uncommon epidermal tumor that exhibits a keratinizing surface with the formation of a cutaneous horn and that clinically resembles a hyperkeratotic actinic keratosis. Histologically, there is verrucous hyperplasia of the epidermis with orthokeratotic hyperkeratosis. TK is characterized by abrupt keratinization without formation of a granular cell layer, in the same manner as that in which the outer root sheath keratinizes (trichilemmal keratinization). The epidermis is acanthotic and contains pale-staining keratinocytes. Epithelial lobules and small trichilemmal cysts are connected to the thickened epidermis. We describe the clinical, histologic, and immunohistochemical findings of two cases of TK.