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Competing Interests: The authors have no conflicts of interest to declare.

Competing Interests: The authors have no conflicts of interest to declare.

Background: Lichen planopilaris (LPP) is a primary lymphocytic cicatricial alopecia for which therapy is often ineffective and there is no cure., Objectives: Looking for a new targetable molecule in the treatment of LPP, we sought to verify whether IL-17 expression is increased in scalp biopsies from patients with active scalp lesions of LPP., Methods: Horizontal sections of hematoxylin and eosin-stained slides from 40 scalp biopsies of active LPP were retrospectively collected and stained with the monoclonal antibody against IL-17 (Abcam, Cambridge, MA; ab79056, dilution 1:100). Twenty biopsies from patients with chronic telogen effluvium served as controls because of their morphological resemblance to the normal scalp. Statistical analysis was performed using IBM SPSS Statistics for Windows (IBM Corporation, Armonk, NY)., Results: The main finding was the positive cytoplasmic expression of IL-17 in the perifollicular fibrosis of the affected follicles in LPP which was statistically significant compared with the controls ( P < 0.0001). The labeled cells were identified as fibroblasts based on their spindle shape and fascicular concentric arrangement in tight perifollicular distribution. Although most of the LPP specimens (n = 35; 87.5%) also revealed cytoplasmic IL-17 expression in the lichenoid inflammatory infiltrate, the results were not statistically significant ( P = 0.1351)., Conclusion: Our immunohistochemistry results show that blocking the IL-17 inflammatory pathway may interfere with the progression of the perifollicular fibrosis and inflammation in LPP., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)

Background: Folliculitis decalvans (FD) and lichen planopilaris (LPP) are classified as neutrophilic and lymphocytic cicatricial alopecias according to the North American Hair Research Society. Recently, a clinical phenotype combining concomitant or sequential features for both was described as a FD LPP phenotypic spectrum (FDLPPPS)., Objectives: To review the most common phenotypic presentation of FDLPPPS with a main focus on histopathology., Methods: We reviewed retrospectively series of 7 patients with a similar phenotypic presentation with special focus on the histologic pattern. All patients presented with concomitant features for FD and LPP and recalcitrant course unresponsive to topical and systemic immunomodulatory/anti-inflammatory agents., Results: The most common clinical phenotype was that of hairless patches on the vertex with lost follicular ostia and perifollicular scale and the following diagnostic findings: (1) polytrichia; (2) positive bacterial culture for Staphylococcus in over 50% of the samples isolated from pustules and hemorrhagic crusts; (3) "mixed" histologic features for primary cicatricial alopecia including multicompound follicular structures of average 2-5 follicles (follicular packs), atrophy of the follicular epithelium, lymphohistiocytic infiltrate with granulomas, and prominent plasma cells, but absence of neutrophilic infiltrate in all cases except scarce neutrophils in one; and (4) clinical improvement with adjuvant systemic antimicrobials., Conclusions: The FDLPPPS may be underreported and should be considered in all cases of LPP recalcitrant to treatment. Dermatologists and dermatopathologists should recognize this phenotypic spectrum to guide optimal clinical management consisting of immunomodulatory and anti-inflammatory agents along with systemic antimicrobials.

Background: Frontal fibrosing alopecia (FFA) is an irreversible scarring alopecia, and its incidence has reached epidemic size. Immune privilege collapse of the bulge and epithelial mesenchymal transition play a role in the pathogenesis. We have noted adipose tissue in the dermis in several specimens from FFA., Objective: Our primary objective was to verify the presence of adipose tissue at the isthmus level in biopsies from FFA. Additional objectives included the presence of deep inflammation and position of the sweat coils., Methods: Eighty-three histologic specimens of FFA diagnosed at the Dermatopathology Laboratory at the Department of Dermatology, University of Miami, within 3 years were evaluated retrospectively. All biopsies were bisected horizontally and assessed at several levels. Sixty biopsies from androgenetic alopecia served as controls. Statistical analysis was performed using the χ test. A P value of 0.05 or less was considered significant., Results: Sixty specimens met the inclusion criteria for optimal quality and classic diagnostic features. Seventy percent demonstrated fat tissue infiltration at the isthmus level as clusters of cells or small globules versus 23% of the controls. The fat infiltration in the arrector pili muscle (APM) was present in 55% versus 15% of the controls, and the sweat coils were positioned in the reticular dermis in 43% versus 1.7% of the controls. All results were statistically significant (P < 0.0001). When accounting for the simultaneous presence of any of these 3 variables, 30% of the FFA cases had triple positivity, 61.7% had double positivity, and 75% had at least 1 positive variable versus 0%, 15%, and 10%, respectively, of the controls., Conclusion: New histologic findings in FFA involve the presence of adipose tissue in the dermis. We believe that the close interaction of the hair follicles and the APM with the adipose tissue may play a role in APM degeneration and in epithelial mesenchymal transition.

Frontal fibrosing alopecia (FFA) is an irreversible scarring alopecia with unknown etiology and no cure. The goal is to establish the diagnosis in the early stage, before developing a hairless band of atrophy involving the frontal, temporal scalp and sideburns. Pathology is rarely needed once the disease is clinically apparent. The classic histologic features include follicular dropout with the absence or atrophy of the sebaceous glands and lichenoid lymphohistiocytic infiltrate with concentric layered fibrosis at the upper follicular level. We describe a common pattern that was repeatedly seen in 6 horizontally sectioned scalp biopsies from patients with early presentation of FFA suspected on trichoscopy by the focal presence of peripilar casts around terminal hairs. All biopsies revealed overall preserved follicular architecture with average number of 11 vellus follicles, atrophy of the sebaceous glands, and perifollicular lymphohistiocytic infiltrate involving the outer root sheath of the vellus follicles (n = 5). There was no perifollicular fibrosis of the vellus follicles and no lichenoid inflammation and perifollicular fibrosis of the terminal follicles. This new pattern of "inflammatory vellus involvement" most likely corresponds to an early onset of the disease. The absence of the classic features in such biopsies from early FFA can lead to misdiagnosis.

Background: Patterns in scalp biopsies can overlap, and distinction may be difficult., Objective: To review the current knowledge about the usefulness of special stains and immunohistochemical stains (IHC) for the diagnosis of hair disorders., Methods: The authors used the search engines PubMED, MEDLINE, and MeSH to retrieve articles on the application of special stains and IHC in hair pathology., Results: The authors selected 65 relevant articles discussing the use of special stains and IHC markers in scalp biopsies, including case reports and original articles. No reviews on the subject were found. Although fungal stains, such as periodic acid-Schiff, are very helpful in the diagnosis of noninflammatory tinea capitis, they may be negative in kerion. Elastic stains may help to diagnose end-stage scarring alopecia on vertical sections. Stains for mucin may help to distinguish lupus erythematosus from lichen planopilaris. Lymphocytic markers may assist in the diagnosis of lymphoma-associated alopecia., Conclusions: On a practical level, there is no evidence to recommend the routine use of a stain or a panel of stains in hair pathology. No stain can distinguish between nonscarring and early scarring alopecia. Most IHC stains are currently limited to the experimental and research setting.

Matrical carcinoma (pilomatrix carcinoma) is a rare follicular low-grade malignancy with matrical differentiation. A pigmented variant with admixed dendritic melanocytes is exceedingly rare with only 7 cases reported in the literature. The diagnosis of malignancy can be difficult to establish. The authors report a case of a 79-year-old woman with a matrical carcinoma who presented with an ulcerated nodule on the posterior right leg, measuring 2.2 cm in greatest dimension. The excisional biopsy showed irregularly shaped dermal and subcutaneous nodules ranging in size from 0.1 to 0.5 cm. The nodules were composed of aggregates of large atypical basaloid cells, with multiple, sometimes atypical, mitoses, admixed with ghost cells, and central necrosis en masse. In addition, the neoplasm was characterized by focal marked melanocytic proliferation and multiple whorls of pink eosinophilic material reminiscent of keratin pearls (squamoid whorls). The basaloid cells were positive for beta-catenin both in the nuclei and the cytoplasm and negative for BerEp4. S100, Melan-A, and HMB45 highlighted the melanocytic dendritic cells. Pan-cytokeratin was negative in the ghost cells and focally positive in the squamoid whorls. Squamoid whorls seem to be a significant feature of matrical carcinoma.

The pathologic findings in Central Centrifugal Cicatricial Alopecia (CCCA) have not been studied systematically in horizontal sections. Our objective was to establish the pathologic features, and their frequency in horizontal sections of scalp biopsies obtained from patients with clinically and histologically proven CCCA. Serial horizontal sections of 51 cases were evaluated retrospectively. All biopsies were assessed at 4 levels and at least on 24 horizontal sections. The most common pathologic findings were follicular miniaturization (81% of the cases); premature desquamation of the inner root sheath (96%), focal preservation of the sebaceous glands (94%), which in most of these cases appeared as surrounding "in a hug" an intact vellus follicle; compound follicular structures with perifollicular fibrosis and/or inflammation (89%), lamellar hyperkeratosis/parakeratosis in the hair canal (79%), absent or mild inflammation (77%), and naked hair shafts (68%). Horizontal sections are useful in CCCA to identify early or focal disease and to provide the clinician with better information on the presence of follicular miniaturization, inflammation, and scarring, which can be used to tailor the treatment to the individual patient.

Lymphomatoid papulosis (LyP) is a chronic recurrent lymphoproliferative disorder characterized clinically by self-regressing cutaneous lesions. Histologically, it is recognized by clusters of CD30 atypical lymphocytes in the background of mixed inflammatory infiltrate. It has been classified as type A, B, C, and D. Recently, a further variant of LyP was described as "angioinvasive LyP" in a series of 16 patients. We report a case of a 73-year-old female presenting with papules and nodules on the extremities evolving into eschar-like necrotic plaques. Histological examination revealed medium- to large-sized atypical lymphoid CD30 cells densely infiltrating the dermis with distinct angioinvasion and angiodestruction. No systemic involvement was identified. The clinicopathologic features conformed to the newly described angioinvasive LyP.

Pigmented casts have been reported with variable frequency in scalp biopsies from alopecia areata, trichotillomania, chemotherapy-induced alopecia and postoperative (pressure induced) alopecia. Their presence and morphology in other scalp disorders has not been described. The authors assessed for the presence and morphology of pigmented casts in 308 transversely bisected scalp biopsies from nonscarring and scarring alopecia, referred to the Department of Dermatology, University of Miami within a year. The pigmented casts were present in 21 of 29 cases of alopecia areata (72%), 7 of 7 cases of trichotillomania (100%), 1 case of friction alopecia, 4 of 28 cases of central centrifugal cicatricial alopecia (14%), and 4 of 4 cases of dissecting cellulitis (100%). They did not show any distinguishing features except for the morphology in trichotillomania, which included twisted, linear (zip), and "button"-like pigment aggregation. The linear arrangement was found also in friction alopecia and dissecting cellulitis. Pigmented casts in the hair canals of miniaturized/vellus hairs was a clue to alopecia areata. Pigmented casts can be observed in biopsies of different hair disorders, but they are not specific for the diagnosis. Horizontal sections allow to better assess their morphology and the follicular level of presence of pigmented casts, which in the context of the other follicular findings may be a clue to the diagnosis.

Histopathologic interpretation of horizontal scalp sections is difficult because of the anatomical complexity of the normal pilosebaceous structures in different stages of the hair cycle. The objective of this work was to create a simplified approach that facilitates the diagnosis of horizontal sections. Nine easy to memorize images (photomnemonics) that resemble diagnostic patterns and features in horizontal scalp biopsies were identified after a year of evaluation of horizontal sections. To verify the matched combinations, 2 dermatopathologists and 15 dermatology residents were asked to complete a validation test. After a short PowerPoint introduction, they had to link 9 projected histopathologic slides to the corresponding photomnemonics from the answer sheet. The validation test showed that out of the 153 answered questions, 140 (92%) were correct, which confirms the relevance of the suggested associations: (1) nonscarring alopecias present with a "floral" pattern. The hair follicles and preserved follicular units can be assimilated to different flowers and plants. (2) In scarring alopecias, the most common pattern is the "eyes and goggles" on background of follicular dropout and fibrosis. The photomnemonics method does not substitute the conventional learning of the hair anatomy. It is rather an adjuvant tool that helps dermatopathologists to increase their interest and skills in hair pathology.

Purpose of Review: Wound healing research has progressed impressively over the past years. New insights into the pathogenesis of different chronic wounds and the study of novel treatment have made wound healing a model disorder and have revealed basic cellular and molecular mechanisms underlying chronic wounds. Although the observation is so obvious and simple, the interpretations by different observers can be quite variable. The interpretations of severity and change in severity by treatment may differ considerably between patient and practitioners., Recent Findings: In this review we provide comprehensive view on different aspects of wound diagnostic, including clinical measurement, new biomarkers in wound pathology, proteases evaluation, and future noninvasive sensor-based devices., Summary: Wound caregivers are in the unique position of being able to observe the wound changes and describe these with knowledge and strict methodology, but also with the wide range of available wound diagnostic devices. The complexity of severity assessment in wound healing is reflected by the multiple clinical scores available. The best objective methods used to evaluate cutaneous tissue repair should have a high specificity and sensitivity and a low inter and intraobserver variation.

Anagen effluvium due to chemotherapy is usually reversible with complete hair regrowth. However, there is increased evidence that certain chemotherapy regimens can cause dose-dependent permanent alopecia. The histological features of this type of alopecia and the mechanisms of its origin are not known yet. We discuss the histological features of 10 cases of permanent alopecia after systematic chemotherapy with taxanes (docetaxel) for breast cancer (6 patients), busulfan for acute myelogenous leukemia (3 patients), and cisplatin and etoposide for lung cancer (1 patient). All patients had moderate to very severe hair thinning, which in 4 cases was more accentuated on androgen-dependent scalp regions. Patients complained that scalp hair did not grow longer than 10 cm and showed altered texture. Paired scalp biopsies from the affected scalp areas were obtained and evaluated in serial horizontal and vertical sections. The histology of all specimens was characterized by a nonscarring pattern with a preserved number of follicular units and lack of fibrosis. The hair count revealed decreased number of terminal hairs, increased telogen hairs, and increased miniaturized vellus-like hairs with a terminal to vellus and anagen to telogen ratios of 1:1 and 3.6:1, respectively. There was increased number of fibrous streamers (stelae) in both reticular dermis and subcutis. Arao-Perkins bodies were found in the subcutaneous portions of the streamers. The histological findings of permanent alopecia after chemotherapy are those of a nonscarring alopecia similar to androgenetic alopecia. Dermatopathologists should be aware of this condition as the absence of fibrosis and the presence of miniaturized hairs may be considered as features consistent with a diagnosis of androgenetic alopecia. Hence, these cases could easily be misdiagnosed in the absence of a good clinicopathological correlation.

We describe what we believe to be the seventh report of a combined tumor with histologic features of both malignant melanoma and a squamous cell carcinoma, a squamomelanocytic tumor. An 82-year-old woman presented with a nondescript, skin-colored, firm papule on her nose. Histology showed 2 different neoplastic cell proliferations: atypical squamoid cells and irregularly shaped nests of atypical pigmented epithelioid cells (melanocytes) arranged in small to large nests at the dermal-epidermal junction and within the epidermis. Both components were closely admixed and restricted to the epidermis. Immunohistochemistry showed diffuse cytoplasmic reactivity for pancytokeratin in all areas supporting the histopathologic features of a squamous cell carcinoma. S-100 and melanoma antigen recognized by T cells 1 did not stain these areas and showed strong selective positivity for the atypical melanocytic component. A true malignant proliferation of 2 distinct cell phenotypes due to close paracrine interactions is our favored interpretation because of the intimate admixture, distinct immunohistochemical pattern, and unique histologic features. Perhaps, chronic sun damage (facial location and advanced age) and reduced immunity (history of other malignancies, particularly recent history of a basal cell carcinoma) played a complementary role for the development of the squamomelanocytic tumor.