Lehman, Julia S

ImportanceDirect immunofluorescence (DIF) testing has been an important ancillary tool for the diagnosis of various inflammatory mucocutaneous conditions for more than 50 years. Current DIF test panels are based on historical clinical descriptions; few studies have rigorously addressed preanalytical, analytical, and/or postanalytical aspects, and even fewer have been replicated or validated. Recent unresolved key issues include whether DIF testing and test panels should be triaged or truncated based on clinical indication or histopathologic findings.ObjectiveTo assess levels of consensus regarding practical aspects of DIF testing among immunodermatology testing specialists in the US.Design, Setting, and ParticipantsUsing modified Delphi methods with a priori characterized criteria, a survey containing 54 statements pertaining to DIF testing was created and distributed to assess consensus. Statements not initially reaching consensus were discussed in 2 live virtual sessions, which were supplemented by relevant literature review and free-text survey comments. These statements were then reassessed in a second survey. Immunodermatology testing specialists in US academic institution–based and independent laboratories were invited based on serving as immunodermatology laboratory medical directors, authoring pertinent literature, or delivering relevant talks at major conferences or by referral. The first survey was conducted from January to February 2024, and the second survey was conducted from March to April 2024.Main Outcomes and MeasuresThe primary measured outcome was degree of consensus for various DIF testing practice, including DIF testing triage by histopathology/dermatopathology findings and DIF testing panel tailored truncations by clinical indication.ResultsA total of 23 respondents to the survey invitation had a mean (SD) of 18.5 (11.1) years and median (range) of 20.0 (1.5-46.0) years in immunodermatology laboratory practice. Consensus was achieved for 46 of 54 statements (85.2%) in the initial survey and for an additional 4 statements in the second survey (50 of 54 [92.6%]). Strong consensus was found against tailored truncation of DIF panel based on the clinical indication in the first survey round. The general acceptability of triaging specimens for DIF testing based on histopathology findings remained without consensus after both surveys.Conclusions and RelevanceOverall, participating US specialists in immunodermatology laboratory testing agreed on many practical aspects of DIF testing, including matters not queried previously. The findings also revealed areas of continued controversy and identified issues for prioritized future study.

Background: Controversy exists around the optimal timing of resection of nevus sebaceous (NS). The authors aim to determine optimal timing of NS resection and identify predictors of surgical outcomes and secondary intralesional neoplasms. Methods: Retrospective chart review of all patients with biopsy-proven NS diagnosis treated at the authors' institution between 1987 and 2024. Results: A total of 632 patients (317 females) underwent biopsy at a median age of 17 (interquartile range 11.7–36.9) years. Benign secondary intralesional neoplasms were found in 67 (10.6%) patients, with syringocystadenoma papilliferum being the most common. Malignant secondary intralesional neoplasms were diagnosed in 62 (9.8%) patients, with basal cell carcinoma being the most common. The incidence of secondary intralesional neoplasms was 3.9%, 24.4%, 36.05%, and 54%, in patients aged 0 to 20, 20 to 40, 40 to 60, and 60 to 80 years, respectively (P<0.001). Age and NS area were associated with an increased risk of developing benign and malignant intralesional neoplasms (P=0.01). Younger patients were more likely to need general anesthesia for excision (median age 10.42 versus 17 years, P<0.001). Surgical complications occurred in 10 cases, and 6 patients required unanticipated revision surgery. The risk of developing secondary intralesional neoplasms was similar across different NS anatomic regions (log-rank, P=0.09). Conclusion: Surgical excision of NS is safe and has an acceptable risk profile. The findings of this study support our historic practice of NS excision before puberty (before the accelerated growth phase) to reduce the risk of developing secondary intralesional neoplasms.

Purpose: To review cases of lateral brow dermoid cysts and gain insight into the utility of preoperative imaging, incidence of intraorbital extension, and recurrence rate. Methods: This is a retrospective study of all patients who underwent excision of lateral brow dermoid cysts at the authors' academic center over a 37-year period. Results: A total of 136 patients were included. The median age at presentation was 5.6 months [interquartile range (IQR) 3–16.5], and the median age at removal was 1.5 years (IQR 0.9–3.4). Preoperative imaging was performed in 44 patients. Intraorbital communication was predicted in 4 patients who underwent imaging and confirmed in 6 patients (4.4%) intraoperatively. Superficial dermoids were the most common depth (n=79, 58.1%), followed by periosteal (n=37, 27.2%) and intraosseous (n=14, 10.3%). Two patients (1.4%) presented with postoperative hematoma that required surgical evacuation. Recurrence was seen in 2 patients (1.4%). Among those who completed a follow-up, the median follow-up time was 1 month (IQR 0.44–5.8 months). Conclusion: The authors' study revealed that the majority of lateral brow dermoid cysts are either superficial or involve the periosteum, with orbital involvement being rare. None of our patients demonstrated intracranial communication. Imaging did not seem to add clinical value in patients for whom there was no clinical suspicion for the involvement of the deeper tissues, so careful consideration of ordering preoperative imaging would help decrease health care costs and avoid radiation exposure, which is particularly concerning for pediatric patients. The recurrence rate of lateral brow dermoid cyst seems to be low but studies with longer follow-ups are needed.

Background: Maculopapular cutaneous mastocytosis (MPCM) is a rare disorder characterized by a pathologic accumulation of mast cells in the skin, which may or may not be accompanied by systemic mastocytosis. Diagnosis of MPCM on skin biopsy can be challenging because the findings may be subtle. Although mast cell density in MPCM has been reported, data informing a proposed cutoff for diagnosis and diagnostic criteria are limited. Methods: We identified adult patients diagnosed with MPCM and urticarial tissue reaction/chronic urticaria on skin biopsy and compared the mast cell and eosinophil counts per 1 mm2 in 10 cases each of MPCM, chronic urticaria, and normal skin from routine biopsies. All slides were stained with CD117, and CD117-positive mast cells were counted per 1 mm2 using digital microscopy. Eosinophils were counted on hematoxylin and eosin-stained slides per 1 mm2 using digital microscopy. Results: The median number of mast cells per 1 mm2 was significantly higher in MPCM than in cases of urticaria and normal skin/control tissue (177.3 vs. 26.8 vs. 47.8 mast cell per mm2, respectively; P ≤ 0.001). The calculated “cut point” for mastocytosis versus chronic urticaria and normal skin was 66 mast cells per 1 mm2, whereas the value for controls versus urticaria was 37 mast cells per 1 mm2. Eosinophils had similar density in MPCM and urticaria, and their presence was significant in the differentiation of MPCM and urticaria from normal tissue. Conclusions: This study adds to the literature by providing objective mast cell density data to distinguish challenging cases of cutaneous mastocytosis from urticarial reactions and normal skin. Future studies could explore the development of computer-aided estimations of cellular density with more extensive comparison with other inflammatory conditions to translate our findings more readily into clinical practice.

Objective Dermoid cyst (DC) is a congenital cyst with the potential to have intracranial extension (ICE). This study aims to evaluate the imaging yield and surgical outcomes of nasal, medial brow, forehead, and scalp DCs. Design Retrospective review of craniofacial DCs treated at our institution between 1992 and 2024. Results A total of 117 patients (57 females) were included. The median age at cyst detection and removal were 4.8 months (IQR 3.6-9.6) and 1.8 years (IQR 0.9-5.3), respectively. In 42 patients, parents have noticed the presence of the cyst immediately after birth. Cyst wall rupture during surgical removal was reported in 15.4%. The median follow-up time was 1.3 months (IQR 0.5-12.2). Three patients experienced recurrence. No postoperative complication was reported. The regions with the highest prevalence of ICE were the forehead, frontotemporal scalp, and nasal region. The lateral frontal/temporal scalp had a 33.3% rate of ICE. Midline forehead/scalp lesions demonstrated a higher risk of ICE compared to their lateral equivalents (54.5% vs 17.5%, P = .03). The sensitivity and specificity of magnetic resonance imaging (MRI) were 100% and 95.7%, while for computed tomography (CT scans) were 72.7% and 96.5%. The Area Under the Curve for MRI was 0.978, and for CT was 0.846. The sensitivity and specificity of ultrasound were 50% and 100%. Conclusions Midline forehead/scalp DCs are more prone to extend intracranially than lateral DCs. MRI had a higher sensitivity and specificity than CT scans in detecting ICE. Routine screening imaging should be considered in midline forehead/scalp, lateral frontal/temporal, and nasal DCs.

Abstract: There is a paucity of data regarding porokeratosis confined to the penis and scrotum. We evaluated our single-institutional experience regarding this entity. We interrogated our pathology archive for all specimens from the penis or scrotum, signed out as porokeratosis between 2000 and 2022. Clinical and histopathological features were reviewed, including the number of cornoid lamella(e) per tissue profile and squamous dysplasia. Nine patients were included in the study. The median age at the time of diagnosis was 51 years. Multiple lesions were present in 3 patients. Six patients had exclusively penile involvement, whereas 2 patients had exclusively scrotal involvement. One patient had multiple lesions consistent with porokeratosis ptychotropica, extending from the scrotum to the buttocks and perineum. Clinically, a collarette of scale was noted in 3 patients and diagnosis of porokeratosis was considered in 1 patient before biopsy. Histopathologically, 2 patients exhibited multiple cornoid lamellae in the same profile and 1 patient had follicular cornoid lamellae. Focal squamous dysplasia was only present in 1 patient. Follow-up was available for 5 patients (median duration: 35 months). In 4 patients, the lesions were removed completely during the shave biopsy procedure. At the past follow-up, there were no signs of recurrence or malignant transformation to squamous cell carcinoma in any patient. Porokeratosis involving the penis and/or scrotum may be elusive to diagnosis based on clinical features alone, emphasizing the role of histopathological examination. Increased awareness of this entity may help better delineate its clinicopathological presentation and appropriate classification.

AbstractBackgroundDue to the immune‐mediated nature of non‐infectious cutaneous vasculitis, skin biopsy specimens are often submitted for direct immunofluorescence (DIF) testing when vasculitis is considered clinically. However, evidence regarding the clinical value of DIF has not been rigorously appraised.ObjectiveIn this scoping review, we aimed to systematically evaluate the peer‐reviewed literature on the utility of DIF in vasculitis to assist with the development of appropriate use criteria by the American Society of Dermatopathology.MethodsTwo electronic databases were searched for articles on DIF and vasculitis (January 1975–October 2023). Relevant case series involving more than or equal to three patients, published in English, and with full‐text availability were included. Additional articles were identified manually via reference review. Due to study heterogeneity, findings were analyzed descriptively.ResultsOf 255 articles identified, 61 met the inclusion criteria. Cumulatively representing over 1000 DIF specimens, several studies estimated DIF sensitivity to be 75%. While vascular immunoglobulin A (IgA) deposits on DIF were associated with renal disease, other systemic associations were inconsistent. Vascular IgG deposition may be overrepresented in ANCA‐associated vasculitis. Granular vascular and epidermal basement membrane zone Ig deposition differentiated hypocomplementemic from normocomplementemic urticarial vasculitis. Few studies have assessed the added value of DIF over routine microscopy alone in vasculitis.ConclusionsThis scoping review discovered that DIF testing for vasculitis has been performed not only for diagnostic confirmation of vasculitis but also for disease subtype classification and prediction of systemic associations. Future studies on test sensitivity of DIF compared to that of histopathology are needed.