Psoriasis arthropathica, also known as psoriatic arthritis (PsA), is a highly heterogeneous systemic inflammatory disease. In addition to involving the skin with characteristic psoriatic lesions such as erythematous scaly plaques, it may also affect the joints, leading to joint pain, swelling, stiffness, and functional impairment, thereby substantially reducing patients' quality of life. To develop clinical practice guidelines that align with international standards for guideline development while reflecting Chinese clinical practice, the China Dermatologist Association, in collaboration with the Chinese Dermatovenerology Society of Integrative Medicine, initiated a guideline project focusing on 14 key clinical questions in the diagnosis and management of PsA in China. Evidence-based recommendations were formulated accordingly. This guideline systematically reviews recent domestic and international advances in the diagnosis and treatment of PsA, and covers diagnosis, disease activity assessment, therapeutic strategies, comorbidity management, and pharmacotherapy in special populations. The guideline aims to improve the overall standard of PsA diagnosis and management in China and ultimately enhance patient outcomes.

Pityriasis lichenoides (PL) is a benign, self-limiting inflammatory condition, characterized by the appearance of papular, scaly, or necrotic lesions. Despite the rare incidence, clinicians should suspect its diagnosis in the presence of specific skin lesions and epidemiological contexts, as suggested by its association with infections and/or vaccinations.

Mutations in KRT5, POFUT1, POGLUT1, and PSENEN define four genetic subtypes of Dowling-Degos disease (DDD), with varied clinical and histologic expression including those previously reported as Galli-Galli disease. We report a case of DDD3 associated with a novel early nonsense variant in POGLUT1 (c.12G>A; p.Trp4*), representing, to the best of our knowledge, the first documented case in Spain. A 55-year-old man presented with recurrent pruritic erythematous scaly papules on the trunk and hyperkeratotic brown papules on the cervical and thoracic regions. Direct microscopic examination of scales from erythematous lesions revealed yeast cells and short hyphae compatible with Malassezia sp. Initial histopathologic evaluation of a pigmented papule was interpreted as simple lentigo. Subsequent biopsy demonstrated elongated rete ridges and focal suprabasal acantholysis without dyskeratosis, raising suspicion for DDD. Whole-exome sequencing identified a heterozygous nonsense variant in POGLUT1, confirming the diagnosis of DDD3. Previous studies have shown that diffuse cytokeratin 5 (CK5) expression throughout all epidermal layers may support the diagnosis of DDD3. This case highlights diagnostic pitfalls related to subtle and focal acantholysis, emphasizes the importance of clinicopathologic correlation and serial sectioning.

We report a case of early-onset neonatal pityriasis versicolor (PV) in a term newborn associated with maternal infection. The mother had characteristic hypo- and hyperpigmented, finely scaly lesions over the neck and upper trunk prior to delivery. Within the first weeks of life, the neonate developed multiple hypopigmented, finely scaly macules involving the trunk and proximal thighs. The infant was otherwise clinically well, with no history of prematurity, neonatal intensive care unit admission, antibiotic exposure, or underlying medical illness. The clinical features were consistent with PV, and the diagnosis was confirmed by potassium hydroxide (KOH) microscopy demonstrating Malassezia species in both the mother and infant. Treatment with topical antifungal therapy resulted in clinical improvement. This case highlights that PV, although rare in neonates, can present early in life, particularly in the context of close maternal contact. Increased awareness of this entity may facilitate prompt diagnosis, prevent unnecessary investigations, and ensure appropriate management.

A 52-year-old woman presented with a three-month history of pruritic scaly palmoplantar eruptions that progressed to tense bullae over trunk and extremities along with genital mucosal involvement. Serology confirmed syphilis (VDRL reactive at 1:16 and TPHA positive), and biopsy with direct immunofluorescence (DIF) established bullous pemphigoid (BP). Treatment with benzathine penicillin led to resolution of palmoplantar and genital lesions, but there was no improvement of bullous lesions. Treatment with oral doxycycline and prednisolone significantly resolved the bullous eruptions. In adults, secondary syphilis can rarely be present as bullous eruptions, which may mimic autoimmune blistering disorders like BP, thereby posing a diagnostic dilemma. This case uniquely demonstrates BP persisting despite successful syphilis treatment (8-fold VDRL decrease), requiring ongoing immunosuppression. Unlike previously reported cases where bullous lesions resolved with antibiotics alone, this differential response confirms that syphilis can trigger independent, self-sustaining autoimmune bullous disease.

Cutaneous candidiasis typically affects intertriginous areas and may be overlooked when occurring at non-intertriginous sites. We report a 28-year-old otherwise healthy man with a 7-month history of pruritic scaly erythematous lesions on both upper extremities and the upper abdomen. Before presentation, he had used a topical corticosteroid unsupervised for 2 months. The lesions were initially treated as tinea corporis. Direct microscopy showed pseudohyphae and spores, and two consecutive fungal cultures yielded Candida spp., with CHROMagar Candida supporting Candida albicans. The lesions resolved completely within 2 weeks after oral itraconazole and topical ciclopirox olamine. This case highlights the importance of mycological confirmation in chronic scaly eruptions with unusual distribution, especially in the setting of prior topical corticosteroid exposure.

Mycosis fungoides, the most common subtype of cutaneous T-cell lymphoma, is characterized by an indolent course and a wide spectrum of clinical presentations that frequently mimic benign inflammatory dermatoses. Early-stage disease is particularly challenging to diagnose, often requiring repeated clinicopathologic correlation due to nonspecific histopathologic findings. We present the case of a 64-year-old female with a several-year history of diffuse pruritic skin lesions who was admitted for acute right lower extremity pain, erythema, and swelling concerning cellulitis. While her acute symptoms improved with antibiotic therapy, dermatologic evaluation revealed chronic, widespread hypopigmented and scaly patches and plaques, raising concern for underlying cutaneous T-cell lymphoma. Multiple prior and current skin biopsies demonstrated subacute spongiotic dermatitis without definitive evidence of lymphoma, and immunophenotypic studies, including flow cytometry, were nondiagnostic. This case highlights the diagnostic challenge of suspected early-stage mycosis fungoides, particularly when histopathologic findings are inconclusive and clinical features overlap with common conditions such as cellulitis. The coexistence of an acute inflammatory process may further obscure recognition of an underlying cutaneous lymphoproliferative disorder. Recognition of persistent, atypical, or treatment-refractory dermatologic findings should prompt continued evaluation and consideration of repeat biopsy. This case underscores the importance of maintaining clinical suspicion and integrating longitudinal clinical and pathologic data in the diagnosis of cutaneous T-cell lymphoma.

Psoriasis is a chronic immune-mediated inflammatory disease, and recurrent lesions involving the head and neck can be particularly difficult to manage in clinical practice. Herein, we report a case of recurrent head-and-neck plaque psoriasis treated with stellate ganglion block, an autonomic neuromodulatory intervention. A woman in her 40s had a 6-year history of relapsing plaque psoriasis despite treatment with topical calcipotriol and targeted narrowband ultraviolet-B (UV-B) phototherapy. She declined biologic therapy because of safety concerns. She presented with new erythematous, pruritic plaques on the scalp and neck. Physical examination showed well-defined erythematous, scaly plaques on the forehead, retroauricular regions, and neck. Ultrasound-guided stellate ganglion block was performed with 5 mL of 1% lidocaine, injected alternately into the left and right stellate ganglia once daily for 6 consecutive days. Based on the initial response, a second course was administered, and all other psoriasis treatments were discontinued. Pruritus improved substantially within 48 h of treatment initiation, followed by progressive resolution of erythema and scaling. Complete clearance of the lesions was achieved after two courses of stellate ganglion block. No adverse events were observed, and the patient remained in stable remission during 3 months of follow-up. Although limited to a single case, this observation suggests that stellate ganglion block represents a potential adjunctive therapeutic strategy for patients with recurrent head-and-neck plaque psoriasis. Further studies are warranted to define its efficacy, safety, and mechanistic basis.

Discoid lupus erythematosus is a chronic autoimmune inflammatory dermatosis characterized by erythematous, scaly plaques that may progress to permanent atrophy, scarring, and pigmentary alterations. The auricle is a recognized site of involvement in discoid lupus erythematosus; however, isolated lesions confined to the auricular conchae are less frequently described and may pose diagnostic challenges because of their clinical resemblance to other inflammatory, infectious, or neoplastic conditions of the ear. We report the case of a 35-year-old woman with a 15-year history of asymptomatic bilateral lesions involving the auricular conchae. Physical examination revealed violaceous, poorly defined oval plaques with thick, adherent whitish scale, accompanied by multiple whitish filiform papules consistent with the carpet tack sign. Dermoscopic evaluation demonstrated a violaceous-brown plaque with thick adherent scale, multiple whitish punctate projections, and perifollicular whitish halos. Histopathological examination showed epidermal atrophy, prominent follicular plugging, interface dermatitis with apoptotic keratinocytes, dermal melanophages, thickening of the basal membrane, and increased interstitial mucin, findings consistent with discoid lupus erythematosus. This case highlights the diagnostic value of recognizing characteristic clinical and dermoscopic features, particularly the carpet tack sign, in localized auricular disease. Early identification enables timely diagnosis and appropriate management, thereby helping to prevent irreversible scarring and long-term sequelae in this anatomically and aesthetically sensitive area.

Dermatophytoses are common superficial fungal infections, most frequently caused by Trichophyton species. Among them, Trichophyton tonsurans is increasingly recognized as an important cause of tinea capitis and other dermatophytic infections. We conducted a retrospective review spanning three- years and six months (January 2022 - June 2025) in the Parasitology-Mycology Laboratory of La Rabta University Hospital (Tunis, Tunisia). The study included patients with dermatophytosis confirmed to be caused by Trichophyton tonsurans. Clinical samples (skin, scalp, nails) were examined by direct microscopy, following potassium hydroxide clarification and cultured on Sabouraud agar with chloramphenicol and with or without actidione at 27 °C. Identification was based on colony morphology, microscopic examinations and confirmed by ITS2 sequencing. Eight cases of T. tonsurans infection were diagnosed during the study period. Patients ranged in age from 8 to 59 years. Seven presented with scaly alopecic patches on the scalp and one with generalized erythematous-squamous lesions associated with onychomycosis. Four patients (three children and one adult) reported similar infections among close contacts, suggesting possible intra-familial or community transmission. Direct microscopy was positive in six cases, revealing endothrix parasitism or septate hyphae. Cultures yielded powdery white to beige colonies with a yellowbrown reverse within 8-14 days. Molecular analysis confirmed the isolates as T. tonsurans. This case series documents the occurrence of T. tonsurans infections identified over a recent three-year period in Tunisia. Accurate laboratory diagnosis and molecular confirmation remain essential for clinical management and for monitoring evolving dermatophyte epidemiology in the region.