ERBB2 Amplification and HER2 Expression in Salivary Duct Carcinoma: Evaluation of Scoring Guidelines and Potential for Expanded Anti-HER2 Therapy.

Salivary duct carcinoma (SDC) is aggressive with limited therapeutic options. A subset of SDC display human epidermal growth factor receptor 2 (HER2) protein overexpression by immunohistochemistry, and some show ERBB2 gene amplification. Guidelines for HER2 scoring are not firmly established. Recent advances in breast carcinoma have established a role for anti-HER2 therapies in lesions with low HER2 expression lacking ERBB2 amplification. Delineating HER2 staining patterns in SDC is critical for evaluating anti-HER2 treatments. In total, 53 cases of SDC resected at our institution between 2004 and 2020 were identified. Androgen receptor (AR) and HER2 immunohistochemistry and ERBB2 fluorescence in situ hybridization were performed in all cases. AR expression was scored for percentage positive cells and categorized as positive (>10% of cells), low positive (1%-10%), or negative (<1%). HER2 staining levels and patterns were recorded, scored using 2018 ASCO/CAP guidelines, and categorized into HER2-positive (3+ or 2+ with ERBB2 amplification), HER2-low (1+ or 2+ without ERBB2 amplification), HER2-very low (faint staining in <10% of cells), or HER2-absent types. Clinical parameters and vital status were recorded. Median age was 70 years, with a male predominance. ERBB2-amplified tumors (11/53; 20.8%) presented at lower pT stages (pTis/pT1/pT2; P = .005, Fisher exact test) and more frequently had perineural invasion (P = .007, Fisher exact test) compared with ERBB2 nonamplified tumors; no other pathologic features differed significantly by gene amplification status. In addition, 2+ HER2 staining by 2018 ASCO/CAP criteria was most common (26/53; 49%); only 4 cases (8%) were HER2-absent status; 3+ HER2 staining was found in 9 tumors, and all were ERBB2 amplified. Six patients with HER2-expressing tumors received trastuzumab therapy, including 2 with ERBB2-amplified tumors. Overall survival and recurrence-free survival did not differ significantly based on ERBB2 status. This work suggests that 2018 ASCO/CAP guidelines for HER2 evaluation in breast carcinoma could be applied to SDC. Our findings also show broad overexpression of HER2 in SDC raising the possibility that more patients may benefit from anti-HER2-directed therapies.

Combined utility of p16 and BRAF V600E in the evaluation of spitzoid tumors: Superiority to PRAME and correlation with FISH.

BACKGROUND: Spitzoid melanocytic neoplasms are diagnostically challenging; criteria for malignancy continue to evolve. The ability to predict chromosomal abnormalities with immunohistochemistry (IHC) could help select cases requiring chromosomal evaluation. METHODS: Fluorescence in situ hybridization (FISH)-tested spitzoid neoplasms at our institution (2013-2021) were reviewed. p16, BRAF V600E, and preferentially expressed antigen in melanoma (PRAME) IHC results were correlated with FISH. RESULTS: A total of 174 cases (1.9F:1M, median age 28 years; range, 5 months-74 years) were included; final diagnoses: Spitz nevus (11%), atypical Spitz tumor (47%), spitzoid dysplastic nevus (9%), and spitzoid melanoma (32%). Sixty (34%) were FISH positive, most commonly with absolute 6p25 gain (RREB1 > 2). Dermal mitotic count was the only clinicopathologic predictor of FISH. Among IHC-stained cases, p16 was lost in 55 of 134 cases (41%); loss correlated with FISH positive (p < 0.001, Fisher exact test). BRAF V600E (14/88, 16%) and PRAME (15/56, 27%) expression did not correlate with FISH alone (p = 0.242 and p = 0.359, respectively, Fisher exact test). When examined together, however, p16-retained/BRAF V600E-negative lesions had low FISH-positive rates (5/37, 14%; 4/37, 11% not counting isolated MYB loss); all other marker combinations had high rates (56%-75% of cases; p < 0.001). CONCLUSIONS: p16/BRAF V600E IHC predicts FISH results. "Low-risk" lesions (p16+ /BRAF V600E- ) uncommonly have meaningful FISH abnormalities (11%). PRAME may have limited utility in this setting.

Preferentially expressed antigen in melanoma and p16 expression in acral melanocytic neoplasms.

Acral melanocytic neoplasms often pose diagnostic difficulty. Preferentially expressed antigen in melanoma (PRAME) expression and loss of p16 expression have diagnostic utility in melanocytic tumors. We examined PRAME and p16 expression in 30 acral melanocytic neoplasms (n = 11 nevi; n = 2 dysplastic nevi; n = 7 Spitz nevi; n = 10 acral melanomas). PRAME was scored as % positive nuclei: negative = 0%; 1% to 25% = 1+; 25% to 50% = 2+; 50% to 75% = 3+, or positive: 75% to 100% = 4+. p16 expression was defined as retained (homogeneous or checkerboard) or lost (complete or partial/regionally). PRAME expression was negative in all benign, dysplastic, and Spitz nevi. Conversely, all acral melanomas were diffusely (4+) positive for PRAME expression. p16 expression was retained in all benign acral nevi (8/11 homogeneous, 3/11 checkerboard), completely lost in one dysplastic nevus, and retained in all acral Spitz nevi (3/7 homogeneous, 4/7 checkerboard). p16 was retained in five of 10 acral melanomas (3/10 homogeneous; 2/10 checkerboard), and negative in five of 10 acral melanomas (absent in 3/10, partially lost in 2/10). Our data suggest that 4+ PRAME expression is highly sensitive and specific in the setting of acral melanomas and is a more predictive diagnostic tool compared with p16 immunohistochemistry.

Perineuriomatous nevi: A series of eight cases highlighting unifying pathologic features to avoid misdiagnosis.

BACKGROUND: Perineuriomatous nevi are rare and diagnostically problematic. We report a series of eight perineuriomatous nevi to highlight the diagnostic features. METHODS: Cases were retrospectively reviewed and characterized. RESULTS: Median age was 42.5 years (range 25-64), with equal sex distribution. Lesions occurred on the arm (n = 4), trunk (n = 2), and head/neck (n = 2). Median size was 7.5 mm (range 5-12 mm). Clinical differential diagnoses included atypical nevus (3), blue nevus (1), neurofibroma (1), and dermatofibroma (1). Lesions were circumscribed, dome-shaped (5/8), and biphasic (8/8) with nested epithelioid cells and wavy spindled cells arranged in whorled fascicles in a myxocollagenous stroma. When present, junctional growth was lentiginous (4/8). No cases displayed pleomorphism or mitotic figures. The perineuriomatous component stained positively for epithelial membrane antigen (8/8 focal to diffuse) and CD34 (4/5 focal to diffuse). SOX10 and S100 protein stained all nevoid cells and in some cases a subset of intermingled spindled cells in perineuriomatous areas, where other melanocytic markers were negative. p16 protein expression was uniformly retained (3/3), and p53 negative (0/2). Nevoid cells in most lesions were positive for BRAFV600E (5/7). Ki67 was mildly elevated (~5%) in 3/3 cases. CONCLUSIONS: Recognizing the histopathologic and immunophenotypic features in these unusual nevi helps avoid overdiagnosis.

Ultrastructural examination of skin biopsies may assist in diagnosing mitochondrial cytopathy when muscle biopsies yield negative results.

Ultrastructural evaluation of skin biopsies has been utilized for diagnosis of mitochondrial disease. This study investigates how frequently skin biopsies reveal mitochondrial abnormalities, correlates skin and muscle biopsy findings, and describes clinical diagnoses rendered following the evaluation. A retrospective review of surgical pathology reports from 1990 to 2015 identified skin biopsies examined by electron microscopy for suspected metabolic disease. A total of 630 biopsies were included from 615 patients. Of these patients, 178 also underwent a muscle biopsy. Of the 630 skin biopsies, 75 (12%) showed ultrastructural abnormalities and 34 (5%) specifically showed mitochondrial abnormalities including increased size (n=27), reduced or abnormal cristae (n=23), dense matrices (n=20), and increased number (n=8). Additional findings included lysosomal abnormalities (n=13), lipid accumulation (n=2) or glycogen accumulation (n=1). Of the 34 patients with mitochondrial abnormalities on skin biopsy, 20 also had muscle biopsies performed and nine showed abnormalities suggestive of a mitochondrial disorder including absent cytochrome oxidase staining (n=2), increased subsarcolemmal NADH, SDH, or cytochrome oxidase staining (n=1), or ultrastructural findings including large mitochondrial size (n=5), abnormal mitochondrial structure (n=5), and increased mitochondrial number (n=4). The most common presenting symptoms were intellectual disability (n=13), seizures (n=12), encephalopathy (n=9), and gastrointestinal disturbances (n=9). At last known follow-up, 12 patients had a definitive diagnosis of a mitochondrial disorder. One patient each had Complex I deficiency, Complex III deficiency, Charcot-Marie-Tooth disease, pyruvate dehydrogenase deficiency, and Phelan-McDermid syndrome. Our results suggest that skin biopsy sometimes yields diagnostic clues suggestive of a mitochondrial cytopathy in cases with a negative muscle biopsy.

Role of Immunohistochemistry in the Diagnosis of Pilomatrical Tumors.

Pilomatrical skin tumors harbor mutations in CTNNB1, which encodes for ß-catenin, a downstream effector of the Wnt signaling pathway responsible for the differentiation, proliferation, and adhesion of epithelial stem cells. Therefore, downstream molecules, such as CDX2, LEF-1, and SATB2, in the Wnt signaling pathway could be useful diagnostic markers. Here, we sought to investigate the potential of immunohistochemistry (IHC) to differentiate between pilomatricoma and pilomatrical carcinoma, as well as from other cutaneous adnexal tumors. We studied 88 cases of cutaneous tumors (14 pilomatrical carcinomas, 18 pilomatricomas, 13 basal cell carcinomas, 12 squamous cell carcinomas, 12 sebaceous carcinomas, 10 Merkel cell carcinomas, 7 trichoblastomas, and 2 hidradenocarcinomas) using a broad panel of IHC markers: ß-catenin, SATB2, CDX2, LEF1, Ber-EP4, and PRAME. Pilomatricoma and pilomatrical carcinoma displayed >75% nuclear staining for ß-catenin. CDX2 also strongly stained pilomatrical tumors; however, the staining distribution was limited in pilomatricoma and more widespread in pilomatrical carcinoma. But, overall, it was less than ß-catenin. SATB2 and Ber-EP4 expressions were noted only in a subset of both pilomatrical carcinoma and pilomatricoma, whereas LEF-1 showed strong, diffuse nuclear positivity in both pilomatricoma and pilomatrical carcinoma. Among the IHC markers evaluated, none could distinguish between pilomatricoma and pilomatrical carcinoma. However, the combined use of ß-catenin with CDX2 markers may assist in not only confirming the pilomatrical nature of the proliferation but also in differentiating benign from malignant cases when there is a significant presence of CDX2 staining. Despite these findings, the diagnosis should continue to primarily depend on a thorough histopathologic examination.

Are there specific cytologic features that can predict BRAFV600E mutational status of papillary thyroid carcinoma in fine-needle aspiration specimens?

BACKGROUND: BRAFV600E mutation is the most common molecular alteration found in papillary thyroid carcinoma (PTC) and has been linked to recurrent disease or possibly more aggressive behavior. Some studies have reported sickle-shaped nuclei (SSN) and plump pink cells (PPC) to be predictive markers of BRAF mutation in FNA cytology. We aimed to evaluate the reproducibility of the aforementioned cytologic features. METHODS: A computerized search for diagnosed PTC surgical pathology cases tested for BRAFV600E mutation by Sanger DNA sequencing was performed. Blinded to BRAF results, the corresponding cytology was reviewed for presence of SSN and PPC. Classic nuclear PTC (CNPTC) features, cystic change, and psammoma bodies were also evaluated. The results were correlated with BRAFV600E mutational status and histologic subtypes. RESULTS: Study cohort consisted of 113 cases (74 BRAFV600E mutated, 39 BRAFV600E wild type). SSN and combined CNPTC /SSN had positive predictive value of 74% and 75%, respectively. CNPTC showed 92% sensitivity and 20% specificity. Psammoma bodies had 92% specificity and 5% sensitivity. The presence of combined PPC/SSN showed 80% specificity, 27% sensitivity, and diagnostic accuracy of 45%. CNPTC was seen in 60/61 (98%) SSN and 45/45 (100%) PPC. There was no significant statistical association between SSN, PPC, and CNPTC with specific histologic subtypes and BRAF mutational status. CONCLUSION: CNPTC is sensitive but not specific for BRAF mutational status. SSN, PPC, and CNPTC are not predictive markers for the presence of BRAF mutation or histologic subtypes. Additional studies may be needed to further corroborate these findings.

Phenotypic switch in mycosis fungoides: A tertiary cancer center experience.

BACKGROUND: Changes in immunophenotype in mycosis fungoides (MF) are rarely reported, making this phenomenon a diagnostic challenge with unclear significance for the disease's biological behavior. This study examines a large series of MF patients who exhibited a phenotype switch (PS) and analyzes their clinical and histopathologic characteristics. DESIGN: Institutional files were searched for MF cases exhibiting PS between 2010 and 2020. Clinical, follow-up, and histopathological data were collected. RESULTS: Forty-two biopsies from 32 patients (13 women and 19 men, median age 67.5) showed PS. Eight patients (25 %) experienced multiple PS during their disease course. The median time for PS was 22 months from the initial diagnosis. In 5 cases tested, identical TCR clone peaks were detected in the immunophenotypically distinct lesions. Median follow-up was 14.5 months. Among deceased patients, median time from MF diagnosis to PS was 20.6 months, while among the patients who were still alive, median time was 44.1 months. CONCLUSION: MF biopsies can show PS during the course of the disease and may indicate a change in clinical behavior. 28.1 % of patients displayed more than one PS, further indicating high plasticity of MF cells. No obvious association was found between PS and therapy initiation or response. Features that appeared to portend a worse clinical course were earlier PS in the course of the disease and PS from CD4-/CD8-to CD8+, and CD8+ to CD4-/CD8-. Awareness of this phenomenon is crucial to avoid misdiagnosing phenotypically distinct lymphomas as second primaries and to alert clinicians about potential changes in the disease's clinical course.

Store-and-forward teledermatology impact on diagnosis, treatment and dermatology referrals: Comparison between practice settings.

INTRODUCTION: Store-and-forward (SAF) teledermatology involves non-dermatologists sending clinical images to dermatologists. This improves patient care while reducing unwarranted face-to-face (FTF) specialist office visits. Comparisons between dermatologist diagnostic concordance with referring provider, treatment change recommendations, and FTF referrals have yet to be compared by type of provider and practice setting. METHODS: This retrospective chart review examined SAF teledermatology eConsults from four practice settings: Doctor of Medicine (MD)/Doctor of Osteopathic Medicine (DO) office visits, MD/DO walk-in clinics, nurse practitioner (NP)/physician assistant (PA) office visits and NP/PA walk-in clinics. The most recent 100 MD/DO office- and 100 NP/PA walk-in-referred patient charts were reviewed. There were only 71 NP/PA office and 47 MD/DO walk-in eConsults to review. RESULTS: Teledermatologists agreed with referring provider diagnoses 50% of the time for MD/DO office visits, 29.8% for MD/DO walk-in clinics, 33.8% for NP/PA office visits and 34% for NP/PA walk-in clinics. Diagnostic concordance was significantly higher for eConsults from MD/DO office visits than MD/DO walk-in clinics (p = 0.021), NP/PA office visits (p = 0.035) or NP/PA walk-in clinics (p = 0.022). There were significantly more treatment changes recommended after walk-in eConsults than office visits (67 versus 44%, p < 0.0001). FTF visits were recommended more after office visits than walk-in clinics (46 versus 27%, p = 0.001). Overall, 21% (68/318) of patients ultimately attended FTF appointments. DISCUSSION: SAF teledermatology improves diagnosis, reducing barriers to specialty care. Overall, potential FTF visit reduction was 79%. Expanding eConsult programmes, particularly in walk-in settings, and for use by NP/PAs or early career internists, may render dermatological care more expeditiously and avoid unnecessary FTF visits.

Perilipin 5 links mitochondrial uncoupled respiration in brown fat to healthy white fat remodeling and systemic glucose tolerance.

Exposure of mice or humans to cold promotes significant changes in brown adipose tissue (BAT) with respect to histology, lipid content, gene expression, and mitochondrial mass and function. Herein we report that the lipid droplet coat protein Perilipin 5 (PLIN5) increases markedly in BAT during exposure of mice to cold. To understand the functional significance of cold-induced PLIN5, we created and characterized gain- and loss-of-function mouse models. Enforcing PLIN5 expression in mouse BAT mimics the effects of cold with respect to mitochondrial cristae packing and uncoupled substrate-driven respiration. PLIN5 is necessary for the maintenance of mitochondrial cristae structure and respiratory function during cold stress. We further show that promoting PLIN5 function in BAT is associated with healthy remodeling of subcutaneous white adipose tissue and improvements in systemic glucose tolerance and diet-induced hepatic steatosis. These observations will inform future strategies that seek to exploit thermogenic adipose tissue as a therapeutic target for type 2 diabetes, obesity, and nonalcoholic fatty liver disease.

Nuclear Perilipin 5 integrates lipid droplet lipolysis with PGC-1α/SIRT1-dependent transcriptional regulation of mitochondrial function.

Dysfunctional cellular lipid metabolism contributes to common chronic human diseases, including type 2 diabetes, obesity, fatty liver disease and diabetic cardiomyopathy. How cells balance lipid storage and mitochondrial oxidative capacity is poorly understood. Here we identify the lipid droplet protein Perilipin 5 as a catecholamine-triggered interaction partner of PGC-1α. We report that during catecholamine-stimulated lipolysis, Perilipin 5 is phosphorylated by protein kinase A and forms transcriptional complexes with PGC-1α and SIRT1 in the nucleus. Perilipin 5 promotes PGC-1α co-activator function by disinhibiting SIRT1 deacetylase activity. We show by gain-and-loss of function studies in cells that nuclear Perilipin 5 promotes transcription of genes that mediate mitochondrial biogenesis and oxidative function. We propose that Perilipin 5 is an important molecular link that couples the coordinated catecholamine activation of the PKA pathway and of lipid droplet lipolysis with transcriptional regulation to promote efficient fatty acid catabolism and prevent mitochondrial dysfunction.