BACKGROUND: Existing literature has questioned the sensitivity of patch testing (PT) with cotrimoxazole (CTX) in the study of drug hypersensitivity.
OBJECTIVE: Assess the sensitivity of PT with CTX in non-immediate cutaneous adverse drug reactions (CADR).
METHODS: Retrospective analysis (2000-2022) of PT with an antibiotic series including CTX 10% pet (Chemotechnique Diagnostics©) performed according to ESCD guidelines in patients with suspected non-immediate CADR reactions to CTX. Some patients were additionally tested with in-house preparations of CTX from Bactrim DS® tablets at 10% in pet or water and trimethoprim 10% pet (Laboratórios Edol©).
RESULTS: Sixty-four patients (48F/16M; mean age 47 ± 18) were included, mostly with maculopapular exanthema (51, 80%). Notably, CTX was sole suspect in 24 patients. There was no positive reaction to CTX at 10% from Chemotechnique or Bactrim DS® tablets prepared at 10% pet for patch testing. One patient reacted exclusively to trimethoprim with 1+ reaction. Two patients had a faint reaction (1+) only with the powder of Bactrim DS® tablets in water at D2, but as the reactions faded completely in 24 or 48 h, they were interpreted as irritant non-specific reactions.
CONCLUSIONS: These findings suggest that patch testing may lack sufficient sensitivity to diagnose CTX-induced non-immediate CADR. Therefore, clinicians should be cautious interpreting CTX patch test results.

Epithelioid hemangioendothelioma (EHE) is a rare vascular tumor with metastatic potential. EHE can have single- or multiorgan involvement, with presentations ranging from asymptomatic disease to pain and systemic symptoms. The extremely heterogeneous clinical presentation and disease progression complicates EHE diagnosis and management. We present the case of a 24-year-old woman with two periauricular erythematous papules, leading to the discovery of metastatic EHE through routine biopsy, despite a noncontributory medical history. Histology revealed the dermal proliferation of epithelioid cells and vacuoles containing red blood cells. Immunohistochemistry markers consistent with EHE solidified the diagnosis. Although extremely rare, prompt diagnosis of EHE is essential for informed decision-making and favorable outcomes. Key clinical and histopathological findings are highlighted to aid dermatologists in diagnosing and managing this uncommon condition.

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Cutaneous leishmaniasis is atypical in Sri Lanka because Leishmania donovani, which typically causes visceral disease, is the causative agent. The origins of recently described hybrids between L. donovani and other Leishmania spp. usually responsible for cutaneous leishmaniasis remain unknown. Other endemic dermotropic Leishmania spp. have not been reported in Sri Lanka. Genome analysis of 27 clinical isolates from Sri Lanka and 32 Old World Leishmania spp. strains found 8 patient isolates clustered with L. tropica and 19 with L. donovani. The L. tropica isolates from Sri Lanka shared markers with strain LtK26 reported decades ago in India, indicating they were not products of recent interspecies hybridization. Because L. tropica was isolated from patients with leishmaniasis in Sri Lanka, our findings indicate L. donovani is not the only cause of cutaneous leishmaniasis in Sri Lanka and potentially explains a haplotype that led to interspecies dermotropic L. donovani hybrids.

Metastatic Crohn\'s disease is the rarest cutaneous manifestation of Crohn\'s disease, it presents as cutaneous lesions in areas that are anatomically non-contiguous with the gastrointestinal tract. It requires a high index of suspicion for diagnosis which is confirmed on histopathology. Infliximab can be an effective treatment.

BACKGROUND: Cutaneous squamous cell carcinoma (cSCC) is one of the most common skin cancers worldwide. Due to the ever-increasing sun exposure and life expectancy, cSCCs are increasing worldwide. The aim of our study was to identify specific risk factors leading to local and regional recurrences, determine patients\' survival rates, and identify best practices for the management of cSCC.
METHODS: This study retrospectively analyzed 1197 head and neck cSCCs in 945 patients who consecutively presented to the clinics from January 2007 to December 2016. Patients were followed up for a minimum of 18 months.
RESULTS: A total of 29 patients (3%) developed loco-regional recurrences (26 local, one regional, and two both local and regional) with a median time to recurrence of 25 (range, 1-81) months. The mean follow-up was 32 (range, 5-90) months. Treatment modality (p=0.027), depth of invasion (p<0.001), diameter > 20 mm (p<0.001), gender (p=0.022), histological differentiation (p<0.001), site of the lesion (p<0.001), perineural and intravascular invasion (p<0.001), positive lymphadenopathy (p=0.021), immunosuppression (p<0.001), and history of treatment (p=0.008) proved to be strong predictors for loco-regional recurrences. At one and five years after diagnosis, 95.6% and 59.9% of all patients were recurrence-free, respectively. The median survival time from recurrence was 2.6 years.
CONCLUSIONS: Our study identifies prognostic indicators for reoccurrence by analyzing data from a large continuous cohort in the management of cSCCs.

Scalp lesions associated with psoriasis and cutaneous leishmaniasis can be clinically indistinguishable, leading to misdiagnosis. Herein, we highlight a 70-year-old male initially misdiagnosed with psoriasis but subsequently confirmed to have cutaneous leishmaniasis. This emphasizes the importance of considering alternative diagnoses, especially in atypical presentations, to ensure accurate treatment.

Rosai-Dorfman disease (RDD) is a rare disorder characterized by excessive growth of histiocytes. We present a case of a 14-year-old female with cutaneous RDD who had a subcutaneous lump on her left arm for three years. The lump became tender and progressively larger over the past year. She had no systemic symptoms, and her physical examination revealed a mobile, tender lump. Laboratory tests were normal. Surgical excision of the lump was performed, and histopathological examination confirmed RDD with the presence of epithelioid histiocytes with eosinophilic and clear cytoplasm, along with emperipolesis and positive staining for CD68, CD163, S100, and OCT2. The patient was referred for follow-up and required no further treatment. RDD can present with subcutaneous masses without systemic symptoms, and it is important to consider RDD in the differential diagnosis of such cases. Surgical excision is the main treatment, and long-term monitoring is necessary due to the potential for disease recurrence. Awareness of cutaneous RDD presentations is crucial for accurate diagnosis and management.

Cutaneous imaging is a central tenant to the practice of dermatology. In this article, the authors explore various noninvasive and invasive skin imaging techniques, as well as the latest deployment of these technologies in conjunction with the use artificial intelligence and machine learning. The authors also provide insight into the benefits, limitations, and challenges around integrating these technologies into dermatologic practice.

OBJECTIVE: The research outlines anatomical landmarks that may help surgeons in identifying the lateral antebrachial cutaneous nerve (LABCN) to minimize nerve damage during procedures in the cubital fossa.
METHODS: Twenty-eight fresh cadaveric upper extremities were dissected. The course of the LABCN was followed from the emerging point at the biceps brachii tendon (BT) to the mid-forearm. The nerve\'s relationships with the BT, lateral epicondyle (LE), antebrachial vein, and brachioradialis (BR) muscle were measured and documented.
RESULTS: The LABCN emerged lateral to the BT in all specimens and crossed medially at the top of the BT in 50% of the cadavers. It was deep to the forearm superficial fascia in all cadavers. At the level of the LE, the nerve was located at a mean of 6.3 ± 3.1 mm medial to the BR. The LABCN aligns with the medial border of the BR at a mean of 68 mm distal to the interepicondylar line. The mean distance from the LE to the LABCN at the interepicondylar line was 24.5 ± 7.2 mm. The LABCN and antebrachial vein are in the same deep fascia plane, on average 47.6 ± 5 mm (37-55) from the LE. At the elbow joint level, 82.1% of the specimens have two branches for the LABCN, whereas 17.9% demonstrated only a single branch.
CONCLUSIONS: Lateral antebrachial cutaneous nerve was situated approximately 6.8 cm distal to the interepicondyle line, positioned at the ulnar edge of the BR, and runs parallel with the antebrachial vein deep to the forearm fascia plane. The nerve crossed over the biceps tendon in 50% of the specimens. These findings suggest that the nerve should be identified 6-7 cm distal to the LE, followed by a proximal dissection.
CONCLUSIONS: This study may help surgeons in identifying LABCN, and reducing the potential risk of LABCN injury.