Atypical Spitz tumor with SQSTM1::NTRK2 fusion: Report of a case with unique spindled cell features.

A host of signature genetic alterations have been demonstrated in Spitz neoplasms, most notably fusions of kinase genes (including BRAF, ALK, ROS1, NTRK1, NTRK3, RET, MET, MAP3K8) or variants in HRAS. While there are multiple reports of rearrangements involving NTRK1 and NTRK3 in Spitz tumors, there are very few reports of NTRK2-rearranged Spitz nevi in the literature. This report presents an NTRK2-rearranged atypical Spitz tumor with spindled cell features.

Histologic and Genetic Features of 51 Melanocytic Neoplasms With Protein Kinase C Fusion Genes.

Fusion genes involving homologs of protein kinase C (PKC) have been identified in a variety of tumors. We report the clinical and histologic presentation of 51 cutaneous melanocytic neoplasms with a PKC fusion gene (involving PRKCA in 35 cases, PRKCB in 15 cases, and PRKCG in a single case). Most tumors were in young adults (median age, 29.

Novel SOX10 indel mutations drive schwannomas through impaired transactivation of myelination gene programs.

Background: Schwannomas are common peripheral nerve sheath tumors that can cause severe morbidity given their stereotypic intracranial and paraspinal locations. Similar to many solid tumors, schwannomas and other nerve sheath tumors are primarily thought to arise due to aberrant hyperactivation of the RAS growth factor signaling pathway. Here, we sought to further define the molecular pathogenesis of schwannomas.

LAMP-enabled diagnosis of Kaposi's sarcoma for sub-Saharan Africa.

Kaposi's sarcoma (KS) is an endothelial cancer caused by the Kaposi's sarcoma-associated herpesvirus (KSHV) and is one of the most common cancers in sub-Saharan Africa. In limited-resource settings, traditional pathology infrastructure is often insufficient for timely diagnosis, leading to frequent diagnoses at advanced-stage disease where survival is poor. In this study, we investigate molecular diagnosis of KS performed in a point-of-care device to circumvent the limited infrastructure for traditional diagnosis.

Microsecretory adenocarcinoma of the skin harboring recurrent SS18 fusions: A cutaneous analog to a newly described salivary gland tumor.

Background: Microsecretory adenocarcinoma (MSA) is a newly described salivary gland neoplasm characterized by MEF2C::SS18 fusions. MSA was previously thought to occur exclusively in salivary glands. Here, we expand the spectrum of known primary sites of this tumor by describing a series of cutaneous tumors with analogous findings.

Cutaneous angiosarcoma presenting as bilateral periorbital edema.

A 66-year-old man presented with chronic bilateral periorbital edema with associated yellowish hue, scattered violaceous smooth macules and contracture of the forehead. He had undergone dental surgery 3 months prior to symptom onset. Laboratory workup for common causes of eyelid edema was unremarkable and MRI of the orbits was unrevealing.

Histopathologic and genetic findings in atypical spindle cell/pleomorphic lipomatous tumors and atypical pleomorphic fibromas.

Background: Spindle cell lipomas, pleomorphic lipomas (SCL/PLs), and pleomorphic fibromas (PF) are tumors with loss of retinoblastoma (RB). The latest World Health Organization classification includes a category of atypical spindle cell/pleomorphic lipomatous tumors (ASPLT), which encompasses tumors in this spectrum that show atypical histopathologic features. We have observed PFs that show similar atypical features.

HPV51-associated Leiomyosarcoma: A Novel Class of TP53/RB1-Wildtype Tumor With Predilection for the Female Lower Reproductive Tract.

Inactivating mutations in tumor suppressor genes TP53 and RB1 are considered central drivers in leiomyosarcomas (LMSs). In high-risk human papillomavirus (HPV)-related tumors, a similar functional outcome is achieved through oncoproteins E6 and E7, which inactivate the p53 and RB1 proteins, respectively. Here, we hypothesized that HPV infection could provide an alternative mechanism for tumorigenesis in a subset of TP53/RB1-wildtype LMS.

Superficial Angiomyxomas Frequently Demonstrate Loss of Protein Kinase A Regulatory Subunit 1 Alpha Expression: Immunohistochemical Analysis of 29 Cases and Cutaneous Myxoid Neoplasms With Histopathologic Overlap.

Superficial angiomyxomas (SAMs) are benign cutaneous tumors that arise de novo and in the setting of the Carney complex (CC), an autosomal dominant disease with several cutaneous manifestations including lentigines and pigmented epithelioid melanocytomas. Although most SAM do not pose a diagnostic challenge, a subset can demonstrate histopathologic overlap with other myxoid tumors that arise in the skin and subcutis. Traditional immunohistochemical markers are of limited utility when discriminating SAM from histopathologic mimics.

Cicatricial pemphigoid Brunsting-Perry variant masquerading as neutrophil-mediated cicatricial alopecia.

A 72-year-old male presented with scarring alopecia on the scalp vertex, multiple crusted plaques on the hairline, and a history of vesicular eruption on the face. The scalp showed crusted plaques with loss of follicular ostia. No follicular pustules or compound follicles were present.

Impact of Next-generation Sequencing on Interobserver Agreement and Diagnosis of Spitzoid Neoplasms.

Atypical Spitzoid melanocytic tumors are diagnostically challenging. Many studies have suggested various genomic markers to improve classification and prognostication. We aimed to assess whether next-generation sequencing studies using the Tempus xO assay assessing mutations in 1711 cancer-related genes and performing whole transcriptome mRNA sequencing for structural alterations could improve diagnostic agreement and accuracy in assessing neoplasms with Spitzoid histologic features.

Primary Cilia Are Preserved in Cellular Blue and Atypical Blue Nevi and Lost in Blue Nevus-like Melanoma.

Distinguishing cellular blue nevi (CBNs) and atypical CBNs from blue nevus-like melanoma (BNLM) can be diagnostically challenging. Immunohistochemistry may inform the diagnosis in a subset of cases but is not always diagnostic. Further, ancillary molecular testing is expensive and often requires significant tissue to complete.

BAP1-inactivated melanocytic tumors show prominent centrosome amplification and associated loss of primary cilia.

Background: BRCA1-associated protein (BAP1) is a tumor suppressor whose loss is associated with various malignancies. The primary cilium is an organelle involved in signal transduction and cell cycle progression. Primary cilia have been shown to be absent in melanoma but retained to some extent in melanocytic nevi, and the severity of dysplasia influences the degree of cilia loss.

Evaluation of Crizotinib Treatment in a Patient With Unresectable GOPC-ROS1 Fusion Agminated Spitz Nevi.

Importance: Spitz nevi are benign melanocytic neoplasms that classically present in childhood. Isolated Spitz nevi have been associated with oncogenic gene fusions in approximately 50% of cases. The rare agminated variant of Spitz nevi, thought to arise from cutaneous genetic mosaicism, is characterized by development of clusters of multiple lesions in a segmental distribution, which can complicate surgical removal.

Cutaneous Leishmaniasis Caused by an Unknown Leishmania Strain, Arizona, USA.

We investigated an autochthonous case of cutaneous leishmaniasis caused by a genetically different Leishmania sp. in a patient in Arizona, USA. This parasite was classified into the subgenus Leishmania on the basis of multilocus DNA sequence and phylogenetic analyses of the rRNA locus and 11 reference genes.