Agminated presentation of fusion-driven melanocytic neoplasms.

BACKGROUND: The conventionally understood pathogenesis of agminated Spitz nevi includes a mosaic HRAS mutation followed by copy number gains in 11p. However, we have recently observed agminated presentations of fusion-driven melanocytic neoplasms. METHODS: We retrieved cases from our database of benign fusion-induced melanocytic neoplasms with an agminated presentation. Both the primary lesion and the secondary lesion were sequenced. TERT-promoter mutational testing and the melanoma fluorescence in situ hybridization assay were also performed. RESULTS: Three cases were included. Two had a PRKCA fusion (partners ATP2B4 and MPZL1) and one had a ZCCHC8::ROS1 fusion. None of the cases met morphologic or molecular criteria for malignancy. There was no evidence of tumor progression in secondary lesions. The same fusion was identified in the primary and secondary lesions. None of the patients developed evidence of nodal or systemic metastasis. CONCLUSIONS: We present accumulating evidence that fusion-driven melanocytic neoplasms can present with an agminated presentation. The differential diagnosis of an agminated presentation versus a locally recurrent or potentially locally metastatic tumor is critical, and accurate diagnosis has significant prognostic and therapeutic consequences for the patient. As with HRAS mutations, fusion-driven melanocytic tumors may have an agminated presentation.

Drug-induced Grover's disease: a case report and review of the literature.

BACKGROUND: Grover's disease (GD) is a relatively rare transient dermatosis that can be idiopathic or acquired. Acquired GD may occur secondary to internal triggers such as medications and malignancies and external factors such as friction. OBJECTIVE: The purpose of this report is to describe the clinical and histological presentation of drug-induced Grover's disease (DIGD) and discuss potential pathogenic mechanisms. METHODS: A systemic review of the literature was performed to identify medications implicated in DIGD. RESULTS: We identified 13 reports of patients with DIGD. Most patients presented with a papular or papulovesicular morphology involving the trunk and extremities. Pruritus was the most common symptom. The majority of the offending agents were cancer therapeutics. Discontinuation of the culprit medication was sufficient for rash clearance and symptom resolution in most cases. CONCLUSION: The overlap in morphology and associated symptoms in DIGD and GD makes the diagnosis of DIGD challenging and has potentially led to underdiagnosis. However, in cases of more extensive involvement and treatment recalcitrance, a drug-induced eruption should be considered.

Poroid adnexal skin tumors with YAP1 fusions exhibit similar histopathologic features: A series of six YAP1-rearranged adnexal skin tumors.

BACKGROUND: Adnexal skin tumors are diagnostically challenging with few known molecular signatures. Recently, however, YAP1-MAML2 and YAP1-NUTM1 fusions were identified in poroid adnexal skin tumors. METHODS: Herein, we subjected eight poroid adnexal skin tumors (three poromas and five porocarcinomas) to fusion gene analysis by whole transcriptome sequencing and next-generation DNA sequencing analysis. RESULTS: YAP1 fusions were identified in six cases. YAP1-NUTM1 fusions were identified in two poromas and three porocarcinomas. A single case of porocarcinoma harbored a YAP1-MAML2 fusion. Two cases were negative for gene fusion. All cases that harbored YAP1-NUTM1 fusions showed nuclear protein in testis (NUT) expression by immunohistochemistry, with NUT being negative in the YAP1-MAML2-positive case. In this case series, we provide a detailed histopathologic description of six YAP1-fused poroid skin tumors, which we show harbor reproducible histopathologic features, to include broad, bulbous tumor tongues with admixtures of basaloid, poroid cells punctuated by squamatized cuticles and ductules, with uniform tumor nuclei featuring frequent grooves and pseudonuclear inclusions. CONCLUSIONS: Awareness of the characteristic histopathologic features of YAP1-fused poroid adnexal skin tumor is a step toward a more reproducible classification of adnexal skin tumors as well as a step toward targeted therapy for metastatic and/or unresectable examples of this poroid group of neoplasms.

Rituximab as an Adjuvant Rescue Treatment for Ocular Cicatricial Pemphigoid.

PURPOSE: Ocular cicatricial pemphigoid (OCP) can lead to devastating ocular complications without prompt treatment. A number of immunomodulatory agents have been attempted with varying success. The objective of this study was to evaluate the use of rituximab as an adjuvant to immunomodulatory treatments (IMTs) in refractory OCP. METHODS: The clinical records of 14 patients with treatment refractory OCP treated with rituximab as monotherapy or in combination with IMTs were retrospectively reviewed, with a focus on demographics, treatments prerituximab and postrituximab, total number of rituximab infusions, response to treatment, and ocular outcomes including staging and best-corrected visual acuity. RESULTS: Thirteen patients (92.9%) achieved a complete response with rituximab over a mean period of 4.3 months. The average sustained complete response time in those without relapse was 29.7 months. Five patients relapsed over a mean period of 15 months, 2 of whom were able to regain control over a mean of 2.5 months with additional rituximab treatments. At the final evaluation, rituximab-based therapy improved ocular outcomes in OCP by stabilizing Foster staging and preventing the deterioration of best-corrected visual acuity in 72% of eyes. In total, 90% of eyes with Foster stages 3 or less did not progress. All patients were able to decrease IMT dosage and/or transition to less potent adjuvant treatments. CONCLUSIONS: The consideration of rituximab earlier in treatment of OCP as a rescue and/or maintenance therapy could result in an earlier arrest of disease progression, resulting in preservation of patients' vision, and enable tapering of adjuvant IMT.

Negative predictive value of biopsy margins of dysplastic nevi: A single-institution retrospective review.

BACKGROUND: Biopsies of dysplastic nevi processed by bread-loafing allow for limited margin assessment; however, reported biopsy margins often influence management. OBJECTIVE: To evaluate the negative predictive value of biopsy margins of dysplastic nevi. METHODS: A retrospective search of a single academic institution's pathology database was conducted to identify all biopsy specimens of dysplastic nevi between January 1, 2015, and December 31, 2017. Biopsy specimen margin assessments were compared with excision pathology reports to calculate negative predictive value and to assess the frequency of residual nevus on excision after positive biopsy margins. RESULTS: A total of 1245 dysplastic nevi from 934 patients were identified. Clear biopsy margins had a negative predictive value for the absence of residual nevus on excision of 87.3% for dysplastic nevi of moderate atypia or greater. Residual nevus was identified on excision in 29.41% of cases of dysplastic nevi of moderate atypia or greater when initial biopsy margins were positive. LIMITATIONS: This was a retrospective, single-institution study. The calculations likely overestimate the true negative predictive value of biopsy margins because of processing of excision specimens by bread-loafing. CONCLUSIONS: This study provides additional evidence that reported biopsy margins are not representative of true margin status.