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Background Intraepidermal acantholysis is a characteristic histopathological feature of pemphigus. The histopathology of scalp biopsies in pemphigus has not been widely discussed in the literature, although the scalp is commonly involved in pemphigus. Methods A total of 32 consecutive patients with scalp involvement (seventeen with pemphigus vulgaris and fifteen with pemphigus foliaceus) were enrolled into the study. The histopathological examination of scalp biopsies was performed in all patients. Tissue specimens were stained with hematoxylin and eosin. Results Acantholysis extended down the entire length of the outer root sheath of the hair follicle in 12/17 (70.6%) patients with pemphigus vulgaris. Follicular acantholysis in pemphigus foliaceus was restricted to the infundibulum and occurred in 12/15 (80.0%) patients. Acantholysis in the vellus hair follicles was observed in 12/17 (70.6%) and 9/15 (60.0%) cases, respectively. The miniaturization of sebaceous glands was seen in 14/17 (82.4%) and 12/15 (80.0%) patients, respectively. Conclusions Follicular acantholysis is a common histopathological feature of pemphigus. It may serve as a clue to the diagnosis of pemphigus subtypes, as pemphigus vulgaris and foliaceus differ in the depth of follicular acantholysis. The miniaturization of sebaceous glands is a common histopathological feature observed in scalp specimens of patients with pemphigus.

Background: Alopecia areata (AA) incognito represents a variant of AA characterized by acute diffuse hair thinning. Dermoscopy shows yellow dots and short regrowing hairs. The differential diagnosis with telogen effluvium (TE) and androgenetic alopecia may be difficult. Methods: In order to establish histopathological criteria for the diagnosis of AA incognito, we evaluated retrospectively 92 specimens (46 horizontal and 46 vertical) of 46 patients diagnosed with AA incognito within 1 year. All specimens were assessed for 20 features, including hair counts and follicular ratios. The numbers were compared with 46 control specimens, consisting of 21 cases of TE and 25 cases of androgenetic alopecia. Results: The following main criteria are proposed: (a) preserved number of follicular units and decreased number of terminal follicles; (b) increased number of telogen structures (mean count of 37%) with presence of at least one telogen germinal unit or/and one small telogen follicle (c) decreased terminal:vellus ratio (mean ratio of 3.3 : 1) and (d) dilated infundibular openings. Conclusion: Two histopathologic clues for AA incognito include the presence of dilated infundibular openings and small basaloid aggregates of cells with round, irregular or polygonal shape, lack of hair shaft and no apoptosis in the outer root sheath, corresponding to small telogen follicles. Miteva M, Misciali C, Fanti PA, Tosti A. Histopathologic features of alopecia areata incognito: a review of 46 cases.

Background: There has recently been controversy regarding whether clone My10 is superior to clone QBEND-10 for labeling cells of tricholemmal lineage. Moreover, there have been no previous reports on the CD34 expression in human vellus hair follicles. Methods: We performed a comprehensive study of the CD34 expression in human terminal and vellus hair follicles and in 10 tricholemmomas using both the QBEND-10 and the My10 clones. We also performed two different procedures of immunostaining, which included the using of the standard avidin-biotin-peroxidase (ABC) complex system and the Envision system. Results: The most sensitive marker of CD34 for normal human hair follicles and tricholemmomas is QBEND-10 using the ABC system. The degree and strength of the CD34 positive staining mainly depended on the method being used (whether it was the ABC system or the Envision system) rather than the clone. CD34 staining was rarely (20–30%) seen in the anagen and catagen vellus hair follicles, and could only be seen by the QBEND-10 clone using the ABC system. CD34 expression in the tricholemmomas represented either a diffuse or peripheral pattern. Conclusions: CD34 may not be a tricholemmal lineage-specific antigen, but may be related to certain functions of the cells. Misago N, Toda S, Narisawa Y. CD34 expression in human hair follicles and tricholemmoma: a comprehensive study.

Generalized basaloid follicular hamartoma syndrome (GBFHS) is a rare, recently-described, autosomal-dominantly inherited disorder that presents with disseminated milia, palmoplantar pitting, hypotrichosis and basaloid follicular hamartomas (BFH). BFH is a benign adnexal tumor that resembles basal cell carcinoma (BCC). In this study, we report two cases of GBFHS and stain BFH, a vellus hair hamartoma (VHH) and a neurofollicular hamartoma (NH) with CD34, bcl-2 and CD10 to characterize and compare the staining patterns of these follicular tumors. Standard immunohistochemistry labeling with CD34, bcl-2 and CD10 was performed on paraffin-embedded, formalin-fixed tissue sections of five BFH (four for CD10), one VHH and one NH. CD34 stromal staining was observed in all specimens. Bcl-2 stained the outermost cell layers of the basaloid nests in all specimens. CD10 stained the peritumoral stroma of all specimens. The BFH, NFH and the VHH showed CD10 staining of matrical cells. CD34 and CD10 stain peritumoral stroma of BFH, VHH and NH. Bcl-2 stains the outermost cell layer of these tumors. CD10 was also observed to stain matrical cells. These results show the similarities in differentiation between these benign follicular neoplasms and trichoepithelioma.

Background: Patterned hair loss, follicular miniaturization, and increased telogen hair counts characterize androgenic alopecia (AGA). Follicular inflammation in AGA has been associated with treatment resistance and progressive hair loss. Case report: Brothers, 15 and 18 years old, presented with frontal and mid-scalp hair loss with an intact frontal hairline noted over a 1-year period. The elder reported past use of androgenic steroids. Laboratory assessment for metabolic and hormonal abnormalities was unrevealing, and hair pull test was negative. Scalp biopsies revealed decreased terminal hairs, marked diameter variation of anagen hairs, decreased terminal to vellus hair ratios (3.7:1/3.4:1, older/younger), and increased telogen counts (23%/21%). Infrabulbar and peri-isthmic (follicular bulge region) lymphocytic infiltrates were present. Hair loss has progressed, unabated by daily topical 0.5% clobetasol (for 6 months), daily 5% minoxidil (1 year), and latter, daily oral finasteride (2 years – older brother only). Discussion: Based on patterned hair loss and miniaturized hairs, these brothers have AGA. The female pattern of hair loss (diffuse hair loss affecting the central scalp with preservation of frontal hair line) coupled with follicular isthmic lymphocytic inflammation represents an unusual presentation, possibly a treatment resistant, inflammatory variant of AGA. The differential diagnosis includes exogenous androgen-mediated hair loss, cicatricial pattern hair loss, or the superimposition of alopecia areata.

Background: Trichotillomania (TM) is a chronic disorder in which patients traumatically remove their own hair in a bizarre pattern. TM histopathological findings are not well defined. Methods: Twenty-eight scalp biopsies of TM were reviewed. Multiple vertical sections and special stains were used to evaluate the specimens. Twenty-six patients (24 female, 2 male) were in the cohort, 2 patients had 2 sets of biopsies. Results: Age range was 13^78 years (mean 41 years), most of them presented with chronic TM. Specific histological findings included trichomalacia (57%) and pigmented casts (46%). Non-specific histological findings included: follicular plugging (96%), decreased number of follicles (96%), reversed anagen:telogen ratio (86%), decreased number of sebaceous glands (68%), melanoderma (68%), increased number of fibrous tracts (64%) and vellus hairs (57%), superficial dermal inflammation (57%), evidence of hemorrhage (18%) and presence of hair granulomas (18%). Conclusions: Even though TM is often a disease of the young people, middle aged and elderly patients with TM have more often a biopsy to confirm the diagnosis. This paper suggests diagnostic criteria for TM. Specific histological findings and clinical suspicion of TM were considered major criteria, while the non-specific histological findings were considered minor diagnostic criteria for TM.

Background: Chloracne is an acneiform eruption due to poisoning by halogenated aromatic compounds having a specific molecular shape. This condition is always a symptom of systemic poisoning by chemical chloracnegens and not just a cutaneous disorder. Methods: We have studied a patient with severe chloracne who showed cutaneous lesions involving mostly the face and the axillae. Results: Histopathologic study of the facial lesions demonstrated that almost every vellus hair follicle was involved, showing a dilated infundibulum filled by a keratotic plug. This keratotic material was mostly composed of orthokeratotic basket-weave basophilic corneocytes, namely infundibular keratin, although there were also some dilated infundibula containing eosinophilic laminated or granular sebum at their center. Small infundibular cysts were more numerous than comedones. Mature and well-developed sebaceous glands were seen at the base of many of the dilated infundibula and no squamous metaplasia of the sebaceous glands or ducts could be demonstrated. Hyperpigmentation of the lesions resulted from hyperproduction of melanin by a normal number of melanocytes along the basal layer of the epidermis and infundibular epithelium. Abundant melanin granules also impregnated the corneocytes of the infundibular plugs. Conclusions: Our findings support the notion that tiny infundibular cysts rather than comedones represent the basic lesions of chloracne.

The trichofolliculoma is a follicularly differentiated hamartoma, usually described as showing many vellus follicles, spreading from a central infundibular cyst. In spite of the well known regressive changes of normal hair follicles during catagen and telogen, the possibility of corresponding changes in the trichofolliculoma has not yet been discussed in the literature. By examining a total of 31 cases of trichofolliculoma it is demonstrated that this hamartoma undergoes an evolutionary process with great morphological changes, which can be attributed to the anagen, catagen, and telogen phase of the follicular cycle.

A 21-year-old male presented with the life-long symptom of slowly growing, easily extractable hair lacking sheath remnants. The distribution and density of all his hair regions appeared normal and there was no alopecia. A hair-pull test was painless and resulted in all hairs being removed, all in keeping with a diagnosis of loose anagen hair syndrome (LAHS). The trichogram was normal. Electronically measured epilation revealed values which were significantly lower than controls. His hair follicles were remarkable for this syndrome in that they looked perfectly normal with light microscopy; however, the segment of the follicle with the keratogenous zone was significantly shorter than normal. It is postulated that a subtle intercellular defect must reside in the line of shear proximal to the level of cuticular differentiation to account for the weak anchoring of the root in the follicle. A consequence of a genetic error probably causes both the weak anchoring and the slow hair growth.

A 67-year-old man is reported with multiple tumors of follicular infundibulum containing ducts. Approximately 30 hypopigmented, scaling macules and minimally elevated papules were present on the face. Skin biopsy specimens from 5 representative lesions revealed similar findings. There was a proliferation of ramifying strands of pale-staining keratinocytes in the upper dermis showing connections with follicular infundibula of vellus follicles and epidermis. There was evidence of hair follicle differentiation with small follicular bulbs, papillary mesenchymal bodies, keratocysts, and occasional hair shafts in the tumor. These findings are characteristic of prior reports of TFI. Ducts were also present within the epithelial cords. Carcinoembryonic antigen, gross cystic disease fluid protein-15, epithelial membrane antigen, and S-100 protein were identified within the tumor. We theorize that the ductal elements within these TFI reflect the multipotential differentiating capacity of portions of infundibular epithelium.

Background: Vellus hair cyst is an uncommon developmental abnormality of the vellus follicle histologically defined as a stratified squamous epithelial-lined cyst containing one or more vellus hairs. Methods: Herein, we report three patients with a heretofore described clinicopathologic condition consisting of multiple contiguous cysts of the ear helices showing solar elastosis and multiple cysts containing vellus hairs, microscopically. Conclusion: Given the anatomic location, history of excessive ultraviolet exposure and pathologic alterations, we surmise that this is a condition related to Favre–Racouchot syndrome, which is predisposed by excessive ultraviolet light exposure.

A 4-year-old male presented with an indurated papular plaque on his right nasolabial fold. The lesion, present since the child was a few months of age, progressively extended in a band-like fashion up to the upper lip. Microscopically, there was almost complete replacement of the hair follicles by trichoepithelioma-like epithelial proliferations associated with hyperplastic sebaceous glands. We interpret this lesion as a localized form of the clinicopathological entity known as generalized hair follicle hamartoma.

Background: Hair counts were studied in scalp biopsy specimens of androgenetic alopecia (AGA) in male and female patients. We also assessed the normal value of hair count in scalp biopsy specimen from Iranians and compared with published data. Methods: Thirty subjects with clinically normal scalps, 25 male and 28 female patients with AGA were studied. Vertical and horizontal sections of 4-mm punch biopsy specimens were examined at various levels from the papillary dermis to the subcutis. Hair counts of total, terminal, vellus, anagen and telogen hairs were obtained by ocular micrometer. Results: Hair counts were not significantly different from published data in American Whites but significantly higher in Iranians compared with Koreans (p

Cutaneous adnexal tumors manifesting divergent differentiation are a rare but recognized subset of adnexal neoplasms. We present a 42-year-old woman with a cystic tumor of the skin above the left eyebrow. A biopsy revealed a tumor comprising eccrine tubules lined by a single row of columnar epithelium surrounded by a peripheral small cuboidal layer and containing, adhered to the internal cuticle, mucin-like material. In some areas, the eccrine tubules were associated with sheets of small plasmacytoid myoepithelial cells embedded in a chondroid matrix. Elsewhere, there were cysts containing central keratinous debris associated with a peripheral basaloid epithelial proliferation showing the formation of buds mimicking abortive hair follicle structures. No polarizable terminal or vellus hairs were seen. These two elements were geographically separate in the biopsy but collided in the center of the tissue element. A diagnosis of benign cutaneous mixed tumor with combined folliculosebaceous and eccrine differentiation was rendered. Such tumors present a diagnostic challenge and are frequently confused with neoplasms including the benign mixed tumor (chondroid syringoma) and a variety of eccrine and folliculosebaceous neoplasms and harmatomata. This case illustrates the potential multilineage differentiation of pluripoential germinative cells of the cutaneous adnexae.

Epithelial cysts are commonly encountered in clinical practice, most usually as epidermoid (infundibular) cysts, and trichilemmal (pilar) cysts. A multitude of other cystic structures can arise from the pilosebaceous unit, including dermoid cyst, pilonidal cyst, eruptive vellus hair cyst, steatocystoma, pilomatricoma, as well as eccrine and apocrine hydrocystoma. Epidermoid cysts are thought to derive from the follicular infundibulum, and express keratin 10 but not keratin 17, whereas trichilemmal cysts are believed to derive from the follicular isthmus, and express both keratins 10 and 17. Proliferating follicular cysts generally exhibit trichilemmal keratinization. In addition to the various aforementioned cysts, hybrid cysts have been reported. The majority of hybrid cysts described have been epidermoid-trichilemmal, in which the upper portion of the cyst shows epidermoid keratinization with a sharp transition inferiorly to trichilemmal keratinization. However other hybrid variants have been reported, including epidermoid-pilomatricoma, epidermoid-apocrine hydrocystoma, trichilemmal-pilomatricoma, eruptive vellus hair cyst-steatocystoma, and eruptive vellus hair cyst-trichilemmal cysts. Here we report, to the best of our knowledge, the first case of a proliferating hybrid cyst containing both epidermoid and trichilemmal components, which presented on the scrotum of a 44-year-old man.

Transverse sectioning of scalp biopsies was first proposed by Headington in 1984. Horizontal sections allow easy analysis of follicular density, accurate determination of hair shaft diameter, and quantification of the anagen:telogen ratio. The terminal to vellus hair (T:V) ratio is an important parameter in the differential diagnosis of non-scarring alopecias. A vellus hair is defined as having a cross-sectional diameter of 0.03 mm or less, and a diameter not exceeding the thickness of its root sheath. It is tedious to tally the T:V ratio in a standard 4 mm punch biopsy because the entire biopsy can only be visualised using the 2x and 4x objectives. It is difficult to identify vellus hairs with this magnification, and one must switch between high and low power, often losing track of which hairs have already been counted. All hair shafts are strongly acid-fast and stain bright red, making it easy to count terminal and vellus hairs with 2x and 4x magnification. We show acid-fast (Ziehl-Zeelsen) stained slides from various types of non-scarring alopecias cut at the level of the infundibula, and contrast these to hematoxylin and eosin stained slides at the same level, to demonstrate how acid-fast staining greatly facilitates follicular counting.

Three hundred and forty-seven tissue specimens were studied from 23 patients with male pattern alopecia. Characteristic features of pattern alopecia included: the presence of miniature or vellus follicles; a marked enlargement of the sebaceous glands and arrectores pilorum muscles; the presence of connective tissue streamers beneath the vellus follicles; and the thinning of the dermis. A mild perivascular infiltrate of mononuclear cells and mild capillary dilatation was sometimes seen. An increased number of mast cells was often a prominent feature. Histochemical procedures were performed for glycogen, acid mucosaccharides, inorganic substances, and enzymes including alkaline phosphatase, acid phosphatase, beta glucuronidase, cholinesterase, aminopeptidase, oxidases and dehydrogenases. Histochemical studies did not reveal any significantly abnormal enzyme changes other than the altered vascular and nerve supply to the the miniature follicles.

In 54 of 325 seborrheic keratoses, trichostasis spinulosa was found within the keratinous cysts and between papillomatous surface keratin, in addition to being present in contiguous hair follicles. Trichostasis in seborrheic keratoses and trichostasis spinulosa are both more frequent in older age groups. Trichostasis spinulosa represents a marker of vellus hair follicles and indicates that some seborrheic keratoses incorporate and may be partially derived from the cells of the infundibular portion of the follicle.