Proliferative, lymphocytic, infundibular mural folliculitis and dermatitis with prominent follicular apoptosis and parakeratotic casts in a Labrador retriever: Clinical, histopathological and dermoscopic features and co-morbidities.

Proliferative, lymphocytic, infundibular mural folliculitis and dermatitis have been reported in six female Labrador retrievers from North America. This is the first report of the disease outside North America, describing the clinical and histopathological diagnosis and dermoscopic aspect of the verrucous plaques, treatment and co-morbidities in a female Labrador retriever dog.

La folliculite et la dermatite murale infundibulaire proliférative, lymphocytaire ont été rapportées chez six Labrador retrievers femelles d'Amérique du Nord. Il s'agit du premier rapport de cette affection en dehors de l'Amérique du Nord, décrivant le diagnostic clinique et histopathologique, l'aspect dermatoscopique des plaques verruqueuses, le traitement et les comorbidités chez une femelle Labrador retriever.

A foliculite e dermatite mural linfocítica infundibular proliferativa tem sido relatada em seis cadelas Labrador retriever da América do Norte. Este é o primeiro relato da doença fora da América do Norte, descrevendo o diagnóstico clínico e histopatológico e o aspecto dermoscópico de placas verrucosas, tratamento de comorbidades em uma cadela Labrador retriever.

Se ha publicado la descripción de una foliculitis y dermatitis mural infundibular, linfocítica y proliferativa en seis hembras de Labrador Retriever de América del Norte. Este es el primer informe de la enfermedad fuera de América del Norte, que describe el diagnóstico clínico e histopatológico y el aspecto dermatoscópico de las placas verrugosas, el tratamiento y las comorbilidades en una perra Labrador Retriever.

Recurrent papulonodular herpes zoster, with syringitis, folliculitis, and vasculitis as clues to the diagnosis.

Herpes zoster (HZ) may have atypical clinical presentations, particularly in immunosuppressed patients. Nodular HZ is an extremely rare condition. We report the first case of recurrent papulonodular HZ in an adult patient with inflammatory bowel disease (IBD) receiving biologic treatment. More interestingly, there was no epidermal involvement on histopathological examination, but the involvement of the adnexa and blood vessels was a clue to the diagnosis in view of the clinical context. We wish to raise awareness of this rare manifestation of HZ for early diagnosis and proper treatment.

Two cases of infancy associated eosinophilic pustular folliculitis (I-EPF) comparing the profile of infiltrating cells with classic EPF by immunohistochemical study.

Infancy associated eosinophilic pustular folliculitis (I-EPF) is a clinical variant of EPF that develops in childhood. Previous studies have suggested that I-EPF exhibits clinical and histological differences distinct from other variants, including classic EPF. Herein, we report two patients with I-EPF treated with topical indomethacin. These two cases exhibited less perifollicular and more perivascular eosinophilic infiltration, which is different in distribution from that of classic EPF. Immunohistochemical study demonstrated that the infiltrating mononuclear cells were CD4-dominant T cells in classic EPF and I-EPF, whereas the number of CD68-positive cells was significantly higher in classic EPF than in I-EPF. Immunohistochemical staining was also performed for eosinophilic pustular folliculitis (HPGDS), which has been reported to induce eosinophils and is a therapeutic target of indomethacin in classic EPF. HPGDS-positive cells were also observed in I-EPF, which may explain the effectiveness of topical indomethacin. Although clinical and histopathological features of I-EPF are different from other variants, the arachidonic acid pathway could be involved in eosinophil infiltration, not only in classic EPF but also in I-EPF.

Granulomatous mural folliculitis in 16 domestic goats: Infection with malignant catarrhal fever viruses and colocalization with ovine herpesvirus-2 using in situ hybridization.

Granulomatous mural folliculitis (GMF) is an uncommon reaction pattern occasionally observed in nonadapted ruminant hosts infected with malignant catarrhal fever viruses. This report characterizes GMF and concurrent cutaneous lesions in 16 goats with crusting dermatitis using histochemistry including hematoxylin and eosin, periodic acid-Schiff, and Grocott's methenamine silver, and immunohistochemistry for CD3, CD20, ionized calcium binding adaptor molecule 1, and cytokeratin AE1/3. Infiltrates in all 16 GMF cases consisted of macrophages and fewer T lymphocytes, and variably included eosinophils, multinucleated histiocytic giant cells, and/or neutrophils. Formalin-fixed paraffin-embedded skin and fresh skin samples from caprine GMF cases were tested using pan-herpesvirus nested conventional polymerase chain reaction (PCR) and partial sequencing, ovine herpesvirus-2 (OvHV-2) real-time PCR, and OvHV-2 colorimetric in situ hybridization (ISH). Five of 16 goats with GMF (31%) were PCR positive for malignant catarrhal fever viruses, including caprine herpesvirus 3 in 1 goat and OvHV-2 in 4 goats. Three goats also had positive intranuclear OvHV-2 hybridization signal in follicular keratinocytes, among other cell types, localized to areas of GMF. Herpesviruses were not detected in the formalin-fixed paraffin-embedded skin of 9 goats without GMF. This case series describes relatively frequent detections of malignant catarrhal fever viruses in the skin of goats with GMF, including the first report of caprine herpesvirus 3, and localizes OvHV-2 infected follicular keratinocytes within areas of GMF.

Widespread, symmetric, noninflammatory alopecia associated with follicular dysplasia in the American red squirrel (Tamiasciurus hudsonicus).

This report describes a unique pattern of alopecia in 8 American red squirrels (Tamiasciurus hudsonicus) from 2013 to 2021. All animals were juveniles; 6 were female and 2 were male. Seven presented between September and November, and one presented in April. All squirrels had widespread, bilaterally symmetric, noninflammatory, well-demarcated alopecia involving the entire trunk and legs and normal hair on their muzzle and dorsal surfaces of their paws. Six months later, a normal hair coat had grown on 2 of the animals, which were littermates. Hair fully grew 2 months later in another animal. Histopathology of the alopecic skin was performed in 7 of 8 animals. The following changes were noted: bent and coiled hairs, perforating folliculitis, melanin clumping, and distortion of hair shafts. Based on features of follicular dysplasia and apparent seasonality, this condition has some similarities to canine seasonal flank alopecia. A genetic etiology is suspected.

Histopathologic Spectrum of Alopecias Seen in a Jamaican Setting.

ABSTRACT: Alopecia is common in Jamaican, primarily Afro-Caribbean patients. We performed a retrospective review examining the histopathologic alopecia diagnoses over ∼5 years. Requisition forms and pathology reports were assessed. Demographic/clinical/technical/diagnostic and pathologic findings of chronicity/severity data were recorded. Three hundred thirty-eight biopsies were included. The majority were 4 mm punches, grossed horizontally. The F:M ratio was 4.8:1, mean age = 42.7 years, and mean duration of alopecia = 5.1 years. Cicatricial alopecias (CAs) predominated over non-CAs (NCAs). The top 10 diagnoses were central centrifugal CA (21.9%), folliculitis decalvans (10.9%), multifactorial alopecias (10.1%), pattern hair loss (8%), lichen planopilaris (7.1%), alopecia areata (6.2%), discoid lupus erythematosus (6.2%), nonclassifiable lymphocytic scarring alopecias (5.6%), frontal fibrosing alopecia (5.3%), and nonspecific NCAs (5%). This contrasted with other richly pigmented populations where discoid lupus erythematosus predominates. Other interesting findings included relatively frequent folliculitis decalvans and lichen planus pigmentosus in 40.9% of frontal fibrosing alopecia cases. Scarring/nonscarring clinicopathologic congruence occurred in 83.4%.Regarding histopathologic features of severity/chronicity, CAs had markedly decreased hair counts. Perifollicular fibrosis affecting retained hairs occurred in 75% of CAs, moderate to severe in >50% of these. Approximately 50% of NCA samples demonstrated advanced miniaturization (T:V ratio <2:1). In our study, relatively young women with chronic hair loss and CA are most frequently biopsied. Central centrifugal CA is the most common diagnosis. Local features of chronic/severe disease are seen microscopically. Clinical impression of scarring/nonscarring correlates well with histopathology.

Alopecia in Patients with Collagen VI-Related Myopathies: A Novel/Unrecognized Scalp Phenotype.

Collagen VI-related myopathies are characterized by severe muscle involvement and skin involvement (keratosis pilaris and impaired healing with the development of abnormal scars, especially keloids). Scalp involvement and hair loss have not been reported among cutaneous changes associated with collagen VI mutations. The aim of this study is to describe the clinical, trichoscopic, and histological findings of the scalp changes in patients affected by COL VI mutations and to estimate their prevalence. Patients with Ullrich congenital muscular dystrophy were enrolled and underwent clinical and trichoscopic examinations and a scalp biopsy for histopathology. Five patients were enrolled, and all complained of hair loss and scalp itching. One patient showed yellow interfollicular scales with erythema and dilated, branched vessels, and the histological findings were suggestive of scalp psoriasis. Two patients presented with scarring alopecia patches on the vertex area, and they were histologically diagnosed with folliculitis decalvans. The last two patients presented with scaling and hair thinning, but they were both diagnosed with folliculitis and perifolliculitis. Ten more patients answered to a "scalp involvement questionnaire", and six of them confirmed to have or have had scalp disorders and/or itching. Scalp involvement can be associated with COL VI mutations and should be investigated.

Efficacy and Safety of Tumour Necrosis Factor-α Antagonists for Folliculitis Decalvans: A Retrospective Case-series Pilot Study.

Folliculitis decalvans is a chronic inflammatory skin disease leading to scarring alopecia. Management of this disabling disease is difficult and no treatment is currently approved. Current knowledge regarding the pathogenesis of folliculitis decalvans suggests the benefit of using anti-tumour necrosis factor-α. This pilot study aimed to evaluate the clinical efficacy of anti-tumour necrosis factor-α for management of folliculitis decalvans. A single-centre retrospective pilot study included patients with refractory folliculitis decalvans treated by tumour necrosis factor-α inhibitors. An Investigator's Global Assessment (IGA) score was designed and validated to assess the efficacy of the therapy. Response to treatment was considered good to excellent when an IGA ≤ 2 was obtained at month 12. Eleven patients were included, with a mean time from diagnosis of folliculitis decalvans to the introduction of infliximab (n = 9) or adalimumab (n = 2) of 8.55 ± 1.26 years. Nine patients had failed on at least 2 lines of systemic therapies before starting anti-tumour necrosis factor-α. The median IGA score at baseline was 3. At the end of follow-up, 5 patients were considered responders. Overall, the safety profile of anti-tumour necrosis factor-α was good. The results suggest that the clinical benefit of anti-tumour necrosis factor-α is obtained after at least 6 months of treatment. However, further prospective studies are needed to confirm these results.

Folliculitis Decalvans Has a Heterogeneous Microbiological Signature and Impaired Immunological Response.

BACKGROUND: Folliculitis decalvans (FD) is a rare primary neutrophilic scarring alopecia whose etiology has not been completely elucidated yet. OBJECTIVE: The aim of the study was to determine if the follicular microbiota residing in FD-affected hair follicles had a distinct microbiological signature and if an aberrant immune response was present in the pathogenesis of FD. METHODS: We conducted a cross-sectional study of 10 patients affected by FD. Trichoscopy-guided follicular biopsies were taken from affected and healthy scalp to identify the follicular microbiome using next-generation sequencing. We searched for microbiological biomarkers of FD-affected follicles using the linear discriminant analysis (LDA) effect size (LEfSe) tool. Additionally, peripheral blood mononuclear cells were obtained, and their cytokine production was quantified after incubation with pathogen-associated molecular patterns isolated from patients' biopsies and compared with healthy controls. RESULTS: ß-diversity analysis showed statistically significant differences regarding bacteria comparing follicular microbiota of healthy and FD-affected hairs. Ruminococcaceae, Agathobacter sp., Tyzzerella sp., and Bacteriodales vadin HA21 family were good predictors of disease status. IL-10, TNF-α, and IL-6 levels were significantly decreased in patients after incubation with various strains of bacteria compared with controls. CONCLUSION: FD hair follicles have a specific heterogenous follicular bacterial microbiota signature. Additionally, these patients seem to have an impaired immunological response.

Aseptic Pustulosis of the Folds Successfully Treated with Methotrexate.

An otherwise healthy 47-year-old woman presented with confluent pustular lesions on the scalp for 5 months and asymptomatic pustular lesions on the trunk and extremities for 2 weeks. She did not have systemic clinical manifestations and was treated with oral antifungals and antibiotics (amoxicillin, and clavulanic acid and flucloxacillin), with no effect. The lesions were unrelated to her menstrual cycle, and she had no history of dermatosis, including acne, psoriasis, or folliculitis. (SKINmed. 2022;20:466-468).

Necrotizing Infundibular Crystalline Folliculitis-A Case Report of a Rare Entity and Review of the Literature.

ABSTRACT: Necrotizing infundibular crystalline folliculitis (NICF) is a rare distinct entity that was introduced in 1999. It typically presents with numerous eruptive waxy papules on the forehead and/or the upper back in adults in their fifth to seventh decade of life. The pathogenesis is unknown to date, but yeast and bacterial infection of the follicular ostia seems to contribute to the development. More recently, NICF has occasionally been observed as a side effect of targeted antitumoral therapy. Histopathologically, NICF is characterized by dilated follicular ostia filled with pale filamentous and birefringent material enclosed by parakeratotic columns of the epidermis and accompanied by a mild superficial inflammatory infiltrate of the dermis. This case report is about a 58-year-old male patient presenting with multiple eruptive keratotic papules on his forehead. Histopathology revealed all classic features of NICF. The case represents a classic example of NICF and is compared with previously published cases that are comprehensively summarized in this article.

Eosinophilic pustular folliculitis developing at the site of COVID-19 vaccination.

We present a rare case of eosinophilic pustular folliculitis due to mRNA-based vaccines for COVID-19. Histology of the biopsy specimen was very interesting.

Eosinophilic Pustular Folliculitis of Infancy: A Histologic Assessment of 43 Cases.

ABSTRACT: Eosinophilic pustular folliculitis of infancy is a sterile, inflammatory dermatosis that mainly affects children younger than 36 months. The underlying physiopathologic mechanism is unclear. Clinical diagnosis is challenging, and a skin biopsy may be necessary. The literature data are sometimes contradictory, and a histologic series of eosinophilic pustular folliculitis of infancy cases has not been previously published.

Giant cutaneous squamous cell carcinoma of the scalp arising in the setting of folliculitis decalvans.

Squamous cell carcinoma (SCC) is uncommon in African Americans (AAs), with an incidence of approximately 0.003%. However, it is the most common skin cancer in that patient population. In AAs, SCC typically arises in sun-protected areas and mainly affects patients older than 50 years. We report a case of giant SCC in an AA man in his 40s with long-standing folliculitis decalvans on the scalp. Three previous skin biopsies were inconclusive. A wide excision was performed and the defect was reconstructed with an anterolateral thigh free flap. Histological analysis of the resected specimen revealed a well-moderately differentiated keratinising SCC with clear cell changes, severe mixed inflammation, folliculitis and dermal scar. He was discharged 2 weeks later and has been followed up closely. Four months later, the patient presents with metastatic SCC to an occipital lymph node.

Atypical folliculitis caused by Malassezia spp. in immunosuppressed patients.

BACKGROUND: Folliculitis due to Malassezia spp. (MF), caused mainly by Malassezia furfur, is clinically characterized by an acneiform eruption expressing follicular papules and pustules, predominantly on the trunk. Diagnosis of MF requires confirmation of the presence of yeasts in the hair follicle. The treatment of choice is topical or oral with azoles. We report two cases of folliculitis due to Malassezia spp. of atypical distribution in immunosuppressed patients. CASE REPORTS: Case 1. We describe a 14-year-old male patient diagnosed with chondroid osteosarcoma who required surgical treatment and chemotherapy. He was hospitalized for fever and neutropenia, presenting a rash of papulopustular lesions on the upper and lower extremities and neck. Direct examination and biopsy were performed to conclude the diagnosis of disseminated atypical Malassezia spp. folliculitis. Case 2. We describe a 16-year-old male patient diagnosed with synovial sarcoma, treated with surgical resection and chemotherapy. During hospitalization due to fever and neutropenia, he presented with disseminated dermatosis of the head, trunk, and upper extremities, showing multiple follicular papules and pustules with erythematous base; on the trunk, there were few lesions. In the supraciliary region, he showed erythema and furfuraceous desquamation. Direct examination of a follicle showed thick-walled round yeasts compatible with MF. CONCLUSIONS: MF is a frequent entity but of low diagnostic suspicion. Immunosuppressed patients may manifest atypical clinical characteristics in non-seborrheic areas, implying diagnostic difficulty. Biopsy and direct examination are essential to corroborate the etiology in patients with immunosuppression or with a non-classical presentation.

INTRODUCCIÓN: La foliculitis por Malassezia spp., causada principalmente por Malassezia furfur, se caracteriza clínicamente por una erupción acneiforme, con pápulas y pústulas foliculares de predominio en el tronco. El diagnóstico requiere confirmar la presencia de las levaduras en el folículo piloso. El tratamiento de elección es tópico u oral con azoles. Se reportan dos casos de foliculitis por Malassezia spp. de distribución atípica en pacientes inmunosuprimidos. CASOS CLÍNICOS: Caso 1. Paciente de sexo masculino de 14 años con diagnóstico de osteosarcoma condroide que ameritó tratamiento quirúrgico y quimioterapia. Fue hospitalizado por fiebre y neutropenia, presentando una erupción con lesiones papulopustulosas en las extremidades superiores e inferiores y en el cuello. Se realizaron examen directo y biopsia para concluir el diagnóstico de foliculitis por Malassezia spp. atípica diseminada. Caso 2. Paciente de sexo masculino de 16 años con diagnóstico de sarcoma sinovial, tratado con resección quirúrgica y quimioterapia, hospitalizado por fiebre y neutropenia. Presentó dermatosis diseminada en la cabeza, el tronco y las extremidades superiores, con múltiples pápulas y pústulas foliculares con base eritematosa; en el tronco había escasas lesiones. En la región supraciliar mostró eritema y escama furfurácea. Se realizó examen directo de un folículo, que reportó levaduras redondas de pared gruesa, compatibles con foliculitis por Malassezia spp. CONCLUSIONES: La foliculitis por Malassezia spp. es una afección frecuente, pero de poca sospecha diagnóstica. En pacientes inmunosuprimidos puede manifestarse con una clínica atípica en áreas no seborreicas, lo que implica la dificultad del diagnóstico. La biopsia y el examen directo son fundamentales para corroborar la etiología en pacientes con inmunosupresión o con expresión no clásica.

Eruptive Necrotizing Infundibular Crystalline Folliculitis: An Expression of an Abortive Sebaceous Follicular Repair Pathway Linked to Committed Infundibular Stem Cells?

ABSTRACT: Necrotizing infundibular crystalline folliculitis is a rare entity, which is a distinctive clinical and histopathological entity. Eruptive yellow waxy umbilicated folliculocentric plugs clinically correspond to pale crystalline filaments embedded in an amorphous sebum-rich material. Remarkably, only the superficial infundibular ostia remain, and the distended cavity is devoid of a follicular or sebaceous gland remnant. The pathogenesis of this enigmatic event remains to be established. The emergence of necrotizing infundibular crystalline folliculitis (NICF) as a paradoxical side effect of antitumor inhibitors epidermal growth factor receptor vascular endothelial growth factor and more recently programmed death-1 represents the expression of altered molecular pathways that underpin the pathogenesis of NICF. To explore these pathways, it is necessary to explore the hierarchy of follicular stem cells, particularly the potential role of committed infundibular stem cells that play a key role in wound healing. Committed infundibular stem cells are closely linked to the sebaceous gland stem cell axis, and this has relevance in the process of homeostatic repair of sebaceous follicles in the wake of folliculitis. The unscheduled modulation of this infundibular homeostatic sebaceous repair axis by epidermal growth factor receptor vascular endothelial growth factor, and programmed death-1 may lead to an aberrant outcome with metaplasia of infundibular keratinocytes to sebocytes. In the absence of sebaceous gland differentiation, these metaplastic infundibular sebocyte cells would lead to the consumption and loss of the infundibulum as a result of holocrine sebum production. This conceptual pathogenic pathway for NICF is constructed by incorporating recent advances in the fields of follicular stem cells, wound repair, follicular homeostasis, regulatory T cells, and molecular pathways linked to the biologicals inducing NICF.

High-fat diet induces a predisposition to follicular hyperkeratosis and neutrophilic folliculitis in mice.

BACKGROUND: Neutrophilic folliculitis is an inflammatory condition of hair follicles. In some neutrophilic folliculitis, such as in patients with acne and hidradenitis suppurativa, follicular hyperkeratosis is also observed. Neutrophilic folliculitis is often induced and/or exacerbated by a high-fat diet (HFD). However, the molecular mechanisms by which an HFD affects neutrophilic folliculitis are not fully understood. OBJECTIVE: Our aim was to elucidate how an HFD promotes the development of neutrophilic folliculitis. METHODS: Mice were fed an HFD, and their skin was subjected to histologic, RNA sequencing, and imaging mass spectrometry analyses. To examine the effect of an HFD on neutrophil accumulation around the hair follicles, phorbol 12-myristate 13-acetate (PMA) was used as an irritant to the skin. RESULTS: Histologic analysis revealed follicular hyperkeratosis in the skin of HFD-fed mice. RNA sequencing analysis showed that genes related to keratinization, especially in upper hair follicular keratinocytes, were significantly upregulated in HFD-fed mice. Application of PMA to the skin induced neutrophilic folliculitis in HFD-fed mice but not in mice fed a normal diet. Accumulation of neutrophils in the skin and around hair follicles was dependent on CXCR2 signaling, and CXCL1 (a CXCR2 ligand) was produced mainly by hair follicular keratinocytes. Imaging mass spectrometry analysis revealed an increase in fatty acids in the skin of HFD-fed mice. Application of these fatty acids to the skin induced follicular hyperkeratosis and caused PMA-induced neutrophilic folliculitis even in mice fed a normal diet. CONCLUSION: An HFD can facilitate the development of neutrophilic folliculitis with the induction of hyperkeratosis of hair follicles and increased neutrophil infiltration around the hair follicles via CXCR2 signaling.