The Impact of Next-generation Sequencing on Interobserver Agreement and Diagnostic Accuracy of Desmoplastic Melanocytic Neoplasms.

Next-generation sequencing (NGS) is increasingly being utilized as an ancillary tool for diagnostically challenging melanocytic neoplasms. It is incumbent upon the pathology community to perform studies assessing the benefits and limitations of these tools in specific diagnostic scenarios. One of the most challenging diagnostic scenarios faced by skin pathologists involves accurate diagnosis of desmoplastic melanocytic neoplasms (DMNs). In this study, 20 expert melanoma pathologists rendered a diagnosis on 47 DMNs based on hematoxylin and eosin sections with demographic information. After submitting their diagnosis, the experts were given the same cases, but this time with comprehensive genomic sequencing results, and asked to render a diagnosis again. Identification of desmoplastic melanoma (DM) improved by 7%, and this difference was statistically significant (P<0.05). In addition, among the 15 melanoma cases, in the pregenomic assessment, only 12 were favored to be DM by the experts, while after genomics, this improved to 14 of the cases being favored to be DM. In fact, some cases resulting in metastatic disease had a substantial increase in the number of experts recognizing them as DM after genomics. The impact of the genomic findings was less dramatic among benign and intermediate-grade desmoplastic tumors (BIDTs). Interobserver agreement also improved, with the Fleiss multirater Kappa being 0.36 before genomics to 0.4 after genomics. NGS has the potential to improve diagnostic accuracy in the assessment of desmoplastic melanocytic tumors. The degree of improvement will be most substantial among pathologists with some background and experience in bioinformatics and melanoma genetics.

BRAF Mutated and Morphologically Spitzoid Tumors, a Subgroup of Melanocytic Neoplasms Difficult to Distinguish From True Spitz Neoplasms.

Drivers of Spitz neoplasms include activating point mutations in HRAS and Spitz-associated genomic fusions. It has become evident that some BRAF -mutated melanocytic neoplasms can morphologically mimic Spitz tumors (STs). These have been termed BRAF mutated and morphologically spitzoid (BAMS). In this study, 17 experts from the International Melanoma Pathology Study Group assessed 54 cases which included 40 BAMS and 14 true STs. The participants reviewed the cases blinded to the genomic data and selected among several diagnostic options, including BAMS, ST, melanoma, and other. A total of 38% of all diagnostic selections in the BAMS cases were for BAMS, whereas 32% were for ST. In 22 of the BAMS cases, the favored diagnosis was BAMS, whereas in 17 of the BAMS cases, the favored diagnosis was ST. Among the 20 cases in the total group of 54 with the highest number of votes for ST, half were BAMS. Of BAMS, 75% had a number of votes for ST that was within the SD of votes for ST seen among true ST cases. There was poor interobserver agreement for the precise diagnosis of the BAMS (kappa = 0.16) but good agreement that these cases were not melanoma (kappa = 0.7). BAMS nevi/tumors can closely mimic Spitz neoplasms. Expert melanoma pathologists in this study favored a diagnosis of ST in nearly half of the BAMS cases. There are BAMS cases that even experts cannot morphologically distinguish from true Spitz neoplasms.

Verruciform Xanthoma: Clinical and Morphologic Spectrum Across Oral, Genital, and Cutaneous Sites.

BACKGROUND: Verruciform xanthoma (VX) is an uncommon, benign epithelial lesion of the oral mucosa. While this entity can also present extraorally, including on the skin and in anogenital areas, the variation in its histologic features in extraoral sites is not yet well defined. Differences in the demographics and morphologic features of oral versus extraoral VX were assessed to help facilitate the accurate diagnosis and management of this lesion. METHODS: After obtaining IRB approval, 110 cases of diagnosed VX were retrospectively collected from our institutional archives spanning from 2000 to 2022. Patient age, gender, available medical history, lesion appearance, and duration were obtained for each case. RESULTS: The median age was 55 years (range 13-86) with a male-to-female ratio of 1.2:1. The most common oral sites, in descending order, were the palate (n = 24, 22%), buccal mucosa (n = 18, 16%), gingiva (n = 16, 15%), and tongue (n = 13, 12%). Extraoral sites comprised 9% of all lesions, including the scrotum (9), vulva (2), cheek (1), wrist (1), gluteal region (1), and abdominal wall (1). The median size for all lesions was 6.0 mm, and extraoral lesions were associated with a 6.7 mm larger size compared to oral lesions (B ± SE: 6.7 ± 2.5 cm, p = 0.01). The lesions were most frequently pink or white in color and often described as papillary, pedunculated, verrucous, and/or exophytic. Microscopically, the presence of wedge-shaped parakeratosis, keratin projections above the epithelium/epidermis, and associated inflammation significantly differed between oral and extraoral lesions. Prominent wedge-shaped parakeratosis (p = 0.04) and keratin projections above the epithelium/epidermis (p < 0.001) were more prevalent in extraoral lesions. There was no significant link between keratin projections and epithelial atypia (p = 0.44). CONCLUSIONS: Familiarity with the broad morphological spectrum of VX, including the presence and degree of wedge-shaped parakeratosis, keratin projections above the epithelium/epidermis, and associated underlying inflammation, will be helpful in diagnosing it in unusual locations.

Revision of the Melanocytic Pathology Assessment Tool and Hierarchy for Diagnosis Classification Schema for Melanocytic Lesions: A Consensus Statement.

Importance: A standardized pathology classification system for melanocytic lesions is needed to aid both pathologists and clinicians in cataloging currently existing diverse terminologies and in the diagnosis and treatment of patients. The Melanocytic Pathology Assessment Tool and Hierarchy for Diagnosis (MPATH-Dx) has been developed for this purpose. Objective: To revise the MPATH-Dx version 1.0 classification tool, using feedback from dermatopathologists participating in the National Institutes of Health-funded Reducing Errors in Melanocytic Interpretations (REMI) Study and from members of the International Melanoma Pathology Study Group (IMPSG). Evidence Review: Practicing dermatopathologists recruited from 40 US states participated in the 2-year REMI study and provided feedback on the MPATH-Dx version 1.0 tool. Independently, member dermatopathologists participating in an IMPSG workshop dedicated to the MPATH-Dx schema provided additional input for refining the MPATH-Dx tool. A reference panel of 3 dermatopathologists, the original authors of the MPATH-Dx version 1.0 tool, integrated all feedback into an updated and refined MPATH-Dx version 2.0. Findings: The new MPATH-Dx version 2.0 schema simplifies the original 5-class hierarchy into 4 classes to improve diagnostic concordance and to provide more explicit guidance in the treatment of patients. This new version also has clearly defined histopathological criteria for classification of classes I and II lesions; has specific provisions for the most frequently encountered low-cumulative sun damage pathway of melanoma progression, as well as other, less common World Health Organization pathways to melanoma; provides guidance for classifying intermediate class II tumors vs melanoma; and recognizes a subset of pT1a melanomas with very low risk and possible eventual reclassification as neoplasms lacking criteria for melanoma. Conclusions and Relevance: The implementation of the newly revised MPATH-Dx version 2.0 schema into clinical practice is anticipated to provide a robust tool and adjunct for standardized diagnostic reporting of melanocytic lesions and management of patients to the benefit of both health care practitioners and patients.

Sweet Syndrome Imitating Cutaneous Cryptococcal Disease.

Cryptococcoid Sweet syndrome is a rare histologic variant of the neutrophilic dermatosis presenting clinically with skin lesions typical of classical Sweet syndrome but with yeast-like structures suggestive of Cryptococcus on histopathology. Histochemical stains for fungus and cultures are negative whereas staining for myeloperoxidase is positive. We present 2 cases of cryptococcoid Sweet syndrome with atypical skin manifestations, including hemorrhagic bullae and plaques, and provide a brief review of the literature. Clinicians should be aware that this variant of Sweet syndrome can present with uncommon clinical findings and has histopathologic findings suggestive of Cryptococcus species.

Cutaneous myoepithelial carcinoma with disseminated metastases.

Primary cutaneous neoplasms of myoepithelial differentiation are uncommon. Cutaneous myoepithelial carcinomas are rare. We report a case of cutaneous myoepithelial carcinoma in a 47-year-old man with a history of end-stage renal disease and renal transplant 19 years prior who presented to the hospital with a 3-month history of diffuse bone pain and an ulcerated scalp mass with multiple satellite lesions. This case illustrates a rare instance of metastatic disease from primary cutaneous myoepithelial carcinoma.

Primary cutaneous perivascular epithelioid cell tumor (PEComa): Five new cases and review of the literature.

PEComas represent a family of uncommon mesenchymal tumors composed of "perivascular epithelioid cells" with a distinct immunophenotype that typically shows both myogenic and melanocytic differentiation. The PEComa family includes angiomyolipoma (AML), clear cell "sugar" tumor of the lung and extra pulmonary sites, lymphangioleiomyomatosis and clear cell myomelanocytic tumor of the falciform ligament/ligamentum teres. Very rarely, PEComas may arise in the skin. Primary cutaneous PEComas typically display a dermal proliferation of epithelioid cells with pale, clear, or granular pink cytoplasm arranged in nests and trabecula with an intervening arborizing network of delicate capillaries. Primary cutaneous PEComas have a lower frequency of myogenic marker expression than their deep soft tissue and visceral counterparts. They also often express strong diffuse CD10, leading to potential confusion with metastatic renal cell carcinoma. Most cases behave indolently. We report 5 additional cases of this rare entity. All showed classic histologic features and expression of either HMB-45 and/or Melan-A/MART-1. Four cases were tested for myogenic markers (2 were positive & 2 were negative). Three cases were tested for CD10 (all 3 were positive). All of our cases with clinical follow-up behaved indolently. Table 1 provides a summary of findings for all 5 cases in our series.

Benign colonic metaplasia at a previous stoma site in a patient without adenomatous polyposis.

There are few reported cases of cutaneous intestinal metaplasia or primary adenocarcinoma arising at the ileostomy site following panproctocolectomy. These complications have been seen almost exclusively in patients with familial adenomatous polyposis and inflammatory bowel disease (IBD). However, benign intraepidermal colonic mucosa at a reversed ileostomy site in a patient without familial adenomatous polyposis or IBD has not been documented. We report a case of a 51-year-old female with a history of colonic adenocarcinoma who presented with pruritic, erythematous, scaly plaques on the right lower abdomen, present since reversal of her ileostomy in 2007. Skin biopsy revealed benign foci of colonic epithelium with no evidence of adenomatous change. Benign intraepidermal colonic mucosa was diagnosed based on histopathologic findings and immunohistochemistry. To our knowledge, this is the first case of intraepidermal benign colonic metaplasia forming in a patient following ostomy reversal. The case emphasizes the importance of patient education and physical examination of the stoma or stoma remnants for detection of unusual or changing lesions due to the risk for malignant transformation. It also demonstrates that benign colonic mucosa should be considered in the differential diagnosis when evaluating lesions near ileostomy sites, regardless of whether the patient has a history of familial adenomatous polyposis or IBD.

Primary cutaneous adenoid cystic carcinoma of the scalp with p16 expression: a case report and review of the literature.

INTRODUCTION: Adenoid cystic carcinoma (ACC) is a rare carcinoma that typically arises in salivary glands but can also occur in other sites including skin. Primary salivary ACC is a locally aggressive tumor characterized by local recurrence and late metastasis. Primary cutaneous ACC is found predominately on the scalp and is more indolent than salivary ACC; and, despite a high incidence of local recurrence, metastases are exceedingly rare. METHODS: A 62-year-old white male presented with a 6-mm mobile, blue-tinted nodule on the left mid scalp unchanged for several years. RESULTS: The histopathological findings of an excisional biopsy were diagnostic for a primary cutaneous ACC. Immunohistochemistry demonstrated focal positivity for p16. CONCLUSIONS: Primary cutaneous ACC is a rare malignancy that should be considered in the differential diagnosis of adnexal neoplasms and, when occurring on the head and neck, must be distinguished from cutaneous involvement by salivary ACC. The majority of reported salivary ACC with p16 protein expression were not positive for high-risk human papilloma virus by in situ hybridization. Immunostaining for p16 has previously been reported in salivary gland ACC. This is the first report in the English literature of p16 immunoexpression in primary cutaneous ACC.

Low-grade fibromyxoid sarcoma with nuclear pleomorphism arising in the subcutis of a child.

Low-grade fibromyxoid sarcoma (LGFMS) represents a rare soft tissue tumor that was first characterized in 1987. LGFMS usually presents as a large, deeply situated mass in adults and is characterized by deceptively bland histopathologic features. LFGMS is less common in superficial soft tissue and in children. It is distinctly uncommon for LGFMS to exhibit nuclear pleomorphism. Herein, we present a case of a 10-year-old male who presented with a subcutaneous back mass that displayed features typical for LGFMS as well as scattered large, hyperchromatic and pleomorphic nuclei. The constellation of clinicopathologic features, including the young age of the patient, the small size and superficial location of the tumor and the presence of scattered nuclear pleomorphism are all unusual features for LGFMS. Fluorescent in situ hybridization (FISH) with a break-apart probe for FUS revealed the presence of a FUS gene rearrangement confirming the diagnosis of LGFMS. This case highlights the importance of maintaining a high index of suspicion for LGFMS even in the context of small, superficially-located tumors, pediatric patients or tumors with scattered nuclear pleomorphism.

Utility of additional tissue sections in dermatopathology: diagnostic, clinical and financial implications.

BACKGROUND: As histopathologic assessment is subject to sampling error, some institutions 'preorder' deeper sections on some or all cases (hereafter referred to as prospective deeper sections), while others order additional sections only when needed (hereafter referred to as retrospective deeper sections). We investigated how often additional sections changed a diagnosis and/or clinical management. Given the recent decrease in reimbursement for CPT-code 88305, we also considered the financial implications of ordering additional sections. METHODS: Cases (n = 204) were assigned a preliminary diagnosis, based on review of the initial slide, and a final diagnosis, after reviewing additional sections. Cases with discordant diagnoses were assessed by two dermatologists, who indicated whether the change in diagnosis altered clinical management. Expenses were estimated for three scenarios: (a) no additional sections, (b) prospective deeper sections and (c) retrospective deeper sections. RESULTS: Diagnoses were modified in 9% of cases, which changed clinical management in 56% of these cases. Lesions obtained by punch-biopsy and inflammatory lesions were disproportionately overrepresented amongst cases with changed diagnoses (p < 0.001, p = 0.12, respectively). The cost of prospective deeper sections and retrospective deeper sections represented a 56% and 115% increase over base costs, respectively. Labor costs, particularly the cost of dermatopathologist evaluation, were the most significant cost-drivers. CONCLUSIONS: While additional sections improve diagnostic accuracy, they delay turn-around-time and increase expenditures. In our practice, prospective deeper sections are cost effective, however, this may vary by institution.

Epithelioid sarcoma-like (pseudomyogenic) hemangioendothelioma, clinically mimicking dermatofibroma, diagnosed by skin biopsy in a 30-year-old man.

Epithelioid sarcoma-like (pseudomyogenic) hemangioendothelioma (ESHE) represents a rare soft tissue and bone tumor that typically presents as nodule(s) in the distal extremities of young adults. The nodules traverse several tissue planes simultaneously and can involve the dermis, subcutis, skeletal muscle and bone. ESHE shares clinical and microscopic features with epithelioid sarcoma (ES), and, accordingly, is commonly misdiagnosed as ES. However, unlike ES, which has a poor prognosis, ESHE commonly follows an indolent course. Herein, we report a case of ESHE diagnosed by skin biopsy that clinically mimicked a dermatofibroma. We also provide clinical photographs of the lesions in various stages of development, representing information that has not been previously published, to our knowledge.

Eosinophilic folliculitis in HIV-infected women: case series and review.

BACKGROUND AND OBJECTIVE: Dermatologic conditions are often presenting signs of HIV infection and may be the sole cause of morbidity in patients who have otherwise stable HIV disease. Eosinophilic folliculitis is a pruritic, follicular eruption that typically manifests late in the course of HIV infection. Most published reports of eosinophilic folliculitis have been in HIV-infected men. In those reports, a characteristic truncal distribution was present, with involvement of the head, neck, and upper extremities commonly seen as well. The objective of this study was to better characterize the presentation of eosinophilic folliculitis in women. METHODS: We conducted a retrospective chart review of six HIV-seropositive women with eosinophilic folliculitis previously seen in our dermatology clinics. We also reviewed the literature for cases of eosinophilic folliculitis in women and for clinical and therapeutic aspects of the condition, particularly in women. RESULTS: In our case series, we found that eosinophilic folliculitis in women may predominantly affect the face and mimic acne excoriée. A review of the literature of HIV-associated eosinophilic folliculitis in women supports these findings. Regarding treatment, many therapies are available, but none is uniformly effective. CONCLUSION: Given the dramatic rise in the incidence of HIV infection in women, who now represent nearly 50% of adults living worldwide with HIV/AIDS, a heightened awareness of HIV-related dermatoses in women is essential. HIV-associated eosinophilic folliculitis should be considered in the differential diagnosis of chronic, pruritic, papular facial eruptions in females.

Salivary duct carcinoma metastatic to inguinal lymph node: a case report of salivary duct carcinoma with distant metastasis diagnosed by fine-needle aspiration.

Salivary duct carcinoma (SDC) is a high-grade malignant tumor exhibiting aggressive growth with early regional and distant metastasis. We report a case of SDC in a 53-yr-old male with distant metastasis to an inguinal lymph node. The diagnosis of the primary tumor as well as the metastatic lesion was accomplished by fine-needle aspiration (FNA). Aggressive clinical management appears to be the main therapeutic option for long-term survival. Therefore, establishing an accurate preoperative diagnosis by FNA can have both clinical and prognostic relevance.

Potential utility of uroplakin III, thrombomodulin, high molecular weight cytokeratin, and cytokeratin 20 in noninvasive, invasive, and metastatic urothelial (transitional cell) carcinomas.

The morphology of urothelial carcinomas, particularly when poorly differentiated or in metastatic sites, is not distinctive and overlaps significantly with other poorly differentiated nonurothelial carcinomas. Currently, there is no widely used single marker or panel of markers to confirm urothelial origin. We evaluated a panel consisting of antibodies to uroplakin III (UROIII), thrombomodulin (THR), high molecular weight cytokeratin (HMWCK), and cytokeratin 20 (CK20) in a wide range of urothelial tumors. Immunohistochemistry was performed on 112 paraffin-embedded urothelial neoplasms: 14 low malignant potential, 16 low-grade noninvasive, 16 high-grade noninvasive, 36 invasive, and 25 metastatic and 5 small cell carcinomas of the urinary bladder. Tissue microarray analysis was used to examine 498 tissue cores of nonurothelial tumors and normal tissue using antibodies to UROIII, THR, and HMWCK. Overall positive staining results in all urothelial tumors are as follows: UROIII, 64 of 112 (57.1%); THR, 77 of 112 (68.8%); HMWCK, 88 of 110 (80%); and CK20, 53 of 110 (48.2%). The expression of the four markers varied with tumor grade and stage. All small cell carcinomas were negative for all markers. Variant morphologic subtypes showed similar staining as conventional urothelial carcinomas. Tissue microarray analysis showed no UROIII immunoreactivity in tissue cores of nonurothelial tumors. THR was expressed by a limited number of nonurothelial cores (10 of 37 [27%] non-small cell lung carcinomas, 2 of 36 [5.6%] lymphomas). HMWCK was expressed by 43.8% of non-small cell lung carcinomas and essentially absent in other nonurothelial tumor cores. Based on the results of the study, the expression of UROIII in a tumor is essentially diagnostic of urothelial origin; however, it is expressed in only slightly more than half of urothelial tumors. The coexpression of THR, HMWCK, and CK20 strongly suggests urothelial origin. The coexpression of two of three non-UROIII markers (THR, HMWCK, CK20) suggests urothelial origin but requires clinicopathologic correlation. The results of the study indicate a role for an antibody panel that includes UROIII, THR, HMWCK, and CK20 in the diagnosis of urothelial tumors.