A pilot study of p53 immunohistochemistry in atypical squamous lesions, using a vulvar scoring system.

BACKGROUND: Histopathologic overlap between cutaneous squamous cell carcinoma (cSCC) and its indolent mimics likely leads to the overdiagnosis of cSCC. OBJECTIVE: To perform a pilot study of the p53 immunohistochemical scoring system developed on vulvar squamous lesions in cSCC. METHODS: The consistency and reliability of p53 immunostaining using a scoring system developed on vulvar cases, as compared with TP53 genomic sequencing, was studied in an initial cohort of 28 cutaneous cases. p53 labeling was further assessed in an additional 63 cases of atypical squamous lesions, including 20 atypical squamous lesions classified by the authors as benign, 22 cases diagnosed as cSCC without high-risk features, and 21 cases of high-risk cSCC (cSCC-HR). RESULTS: The concordance of p53 labeling and TP53 sequencing was 82.1%. Four positive patterns of p53 mutation were identified: basal, parabasal/diffuse, null, and cytoplasmic. p53 positivity in atypical, benign squamous lesions (10%) was significantly lower than that of low-risk cSCC (63.6%, p = 0.0004) or cSCC-HR (90.5%, p < 0.0001). p53 positivity in low-risk cSCC versus cSCC-HR was not statistically significant (p = 0.07). CONCLUSION: p53 Labeling may be a helpful biomarker to support the diagnosis of cSCC and distinguish cSCC from atypical but benign mimics.

Spectrum of Melanocytic Tumors Harboring BRAF Gene Fusions: 58 Cases With Histomorphologic and Genetic Correlations.

We report a series of 58 melanocytic tumors that harbor an activating fusion of BRAF, a component of the mitogen-activated protein kinase (MAPK) signaling cascade. Cases were diagnosed as melanocytic nevus (n = 12, 21%), diagnostically ambiguous favor benign (n = 22, 38%), and diagnostically ambiguous concerning for melanoma (n = 12, 21%) or melanoma (n = 12, 21%). Three main histopathologic patterns were observed. The first pattern (buckshot fibrosis) was characterized by large, epithelioid melanocytes arrayed as single cells or "buckshot" within marked stromal desmoplasia. The second pattern (cords in whorled fibrosis) demonstrated polypoid growth with a whorled arrangement of cords and single melanocytes within desmoplasia. The third pattern (spindle-cell fascicles) showed fascicular growth of spindled melanocytes. Cytomorphologic features characteristic of Spitz nevi were observed in most cases (n = 50, 86%). Most of the cases (n = 54, or 93%) showed stromal desmoplasia. Histomorphology alone was not sufficient in distinguishing benign from malignant melanocytic tumors with BRAF fusion gene because the only histopathologic features more commonly associated with a diagnosis of malignancy included dermal mitoses (P = .046) and transepidermal elimination of melanocytes (P = .013). BRAF fusion kinases are targetable by kinase inhibitors and, thus, should be considered as relevant genetic alterations in the molecular workup of melanomas. Recognizing the 3 main histopathologic patterns of melanocytic tumors with BRAF fusion gene will aid in directing ancillary testing.

Leiomyoma With Massive Lymphoid Infiltration: 2 Cases With Lymphocytic Vasculopathy and Angiocentric Germinal Centers.

Uterine leiomyoma with massive lymphoid infiltration is characterized by a dense lymphoid infiltrate and germinal centers sparing the adjacent myometrium. Only few reports describe this entity and its etiology is unknown. This rare lesion may also exhibit lymphocytic vasculopathy but this has only been reported in the setting of GnRH agonist exposure. We report 2 cases of uterine leiomyoma with massive lymphoid infiltration in which only 1 patient was exposed to GnRH agonists. In both cases, histopathologic analysis showed thick-walled vessels with swollen endothelial cells showing evidence of intramural lymphocytic infiltration, red blood cell extravasation, and medial edema. This constellation of findings represented frank vascular damage and lymphocytic vasculopathy. Our findings suggest that lymphocytic vasculopathy in these lesions may be secondary to factors other than GnRH agonists. Furthermore, both cases showed an angiocentric disposition of germinal centers that has scarcely been alluded to in prior reports. This finding may provide a clue in accurately recognizing leiomyoma with massive lymphoid infiltration. Recognition of this lesion will allow one to avoid mistaking it for mimickers such as inflammatory myofibroblastic tumor, lymphoid malignancies, or other inflammatory processes.

Vulvar Squamous Cell Carcinoma With Sarcomatoid Features are HPV-independent Lesions: A Subset are Also Associated With TP 53-independent Lesions and Radiation Therapy.

Vulvar squamous cell carcinoma of the vulva (VSCC) with sarcomatoid features is a rare variant characterized by spindle-cell morphology and occasional heterologous elements. They are difficult to evaluate due to rarity and lack unified nomenclature and histopathologic criteria. Eight cases of sarcomatoid VSCC were retrieved from archival electronic medical records from 2013 to 2021. Patients often presented at a mean age of 78-yr-old at stage FIGO (2018) III or above. The mean greatest diameter was 4.5 cm and mean depth of invasion was 11.5 mm. Spindle cells exhibited fascicular, nested, and cord-like growth patterns, though a haphazard arrangement or a mix of patterns was frequently observed. The sarcomatoid component frequently arose in the context of prior conventional VSCC treated with radiation therapy (n=6, 75% and chemotherapy (n=5, 63%) with latency periods of 5.2 and 5.4 yr, respectively. Associated lesions included differentiated vulvar intraepithelial neoplasia (n=4, 50%), lichen sclerosus (n=5, 63%), and vulvar acanthosis with altered differentiation (n=1, 13%). Immunohistochemistry showed that VSCC with sarcomatoid features aberrantly expressed p53 (n=4, 60%) through diffuse overexpression or null-type patterns. P16 was invariably negative in all cases. These findings suggest that VSCC with sarcomatoid features does not arise from the HPV-related carcinogenic pathway, and that a subset may also arise from the TP53-independent pathway. Recognizing sarcomatoid morphology in VSCC is important since it may confer an elevated risk of nodal metastasis and poorer survival. Larger studies are required to assess the etiology and prognostic implications of VSCC with sarcomatoid features.

PRAME immunohistochemistry can distinguish melanocytic pseudonests of lichenoid reactions from melanoma in situ.

BACKGROUND: Distinguishing melanocytic pseudonests encountered in lichenoid dermatoses or lichenoid keratoses from melanoma in situ (MIS) with brisk lichenoid inflammation can prove challenging. METHODS: We designed a case-control study to evaluate the accuracy metrics of PRAME immunohistochemistry to distinguish melanocytic pseudonests in lichenoid dermatoses or keratoses from inflamed MIS. Immunostaining for PRAME was performed on paraffin-embedded formalin-fixed diagnostic tissue using a rabbit monoclonal antibody to PRAME (Abcam), with a 1:3200 dilution on a Leica Bond detection system. RESULTS: Our search identified 21 cases of melanocytic pseudonests (n = 21, 46%) encountered in lichenoid dermatoses and 24 cases of inflamed MIS (n = 24, 53%). Each method of evaluating PRAME immunohistochemistry (PRAME+ clusters, PRAME % of melanocytes by four categories and PRAME+ melanocyte counts per linear mm of epidermal basal layer) showed statistically significant differences between the MIS and the pseudonest cohorts (respectively, p < 0.001; p < 0.001; and p < 0.001). Receiver operating characteristics analysis for PRAME+ melanocyte counts per linear mm of epidermal basal layer revealed an area under the curve of 0.9 ± 0.05 (95% confidence interval 0.9-1.0). When determining an optimal cut-off point for the best Youden index [sensitivity (%) + specificity (%) - 100], the cut-off of 1.0 PRAME+ melanocytes per linear mm showed a sensitivity of 79.2% and specificity of 85.7% (Youden index 0.65) to distinguish MIS from pseudonests. CONCLUSION: PRAME immunohistochemistry may constitute an additional tool for this challenging differential diagnosis.

DEVIL, VAAD and vLSC constitute a spectrum of HPV-independent, p53-independent intra-epithelial neoplasia of the vulva.

AIMS: We aimed to characterise a large cohort of non-invasive, human papillomavirus (HPV) and p53-independent verruciform lesions, such as 'vulvar acanthosis with altered differentiation' (VAAD), 'differentiated exophytic vulvar intra-epithelial lesion' (DEVIL) and 'verruciform lichen simplex chronicus' (vLSC). METHODS AND RESULTS: From January 2008 to December 2020 we retrospectively identified 36 eligible patients with verruciform non-invasive lesions (n = 36) and collected clinical, histological and follow-up parameters. Verruciform non-invasive lesions occurred at a median age of 71 years, with a median follow-up of 33.5 months. Clinically, pruritus was only reported in patients with VAAD (n = 3, 21%). Lesion colour was significantly different across categories (P = 0.028). Apart from the histopathological criteria already known to distinguish these entities (hypogranulosis, epithelial pallor and low-magnification architecture), no other significant criteria were discovered and significant overlap was observed, particularly between VAAD and DEVIL. Patients with vLSC trended towards longer survival without recurrence compared to VAAD and DEVIL (P = 0.082), but showed comparable invasion-free survival interval (P = 0.782). Squamous cell carcinomas (SCC) associated with either VAAD, DEVIL or vLSC displayed similar clinical, histopathological and biological parameters. In non-invasive precursor lesions, stromal oedema was associated with invasion (P = 0.015) and remained so upon Cox regression analysis (P = 0.009). CONCLUSION: Our study of HPV and p53 independent non-invasive verruciform lesions of the vulva highlights significant clinical, histopathological and biological overlap between VAAD, DEVIL and vLSC, suggesting that these pre-invasive lesions should be viewed as a spectrum. We also show that stromal features such as oedema might play an import role in progression to invasion.

Age, operation time and surgical approach can be used to detect incidental gallbladder carcinoma in cholecystectomy specimens from low-incidence settings.

AIMS: Gallbladders resected for non-neoplastic diseases are systemically examined microscopically to rule out incidental dysplasia and carcinoma. The main aim of this study was to test whether a pre-grossing algorithm can detect incidental gallbladder carcinoma. The secondary aim was to test whether the algorithm can detect high-grade dysplasia. METHODS AND RESULTS: A retrospective study of clinical, pathological and radiological findings in cholecystectomy recipients was performed on a test set to develop a classification and regression tree algorithm. Cholecystectomy cases were included; exclusion criteria were age <18 years, missing pathology reports, preoperative suspicion of neoplastic disease, and cholecystectomy for non-gallbladder oncological disease. Five thousand nine hundred and eighty-two cholecystectomies from 2006 to 2018 were included in the study, with 18 cases of incidental gallbladder carcinoma and 11 cases of high-grade dysplasia. Three hundred and ninety controls were randomly selected for the testing set. Patient age, surgical approach, operation duration, dilatation of the biliary tract and gallbladder gross anomalies were statistically significant distinguishing factors in multivariate analysis (P < 0.00-0.026). Unsupervised testing with a conditional inference tree suggested that age, procedure type and operation duration can be used to identify incidental gallbladder carcinoma from controls, whereas high-grade dysplasia also requires grossing parameters to identify half of the cases (5/11). CONCLUSION: Readily available clinical parameters and postoperative data can be used to detect incidental gallbladder carcinoma. High-grade dysplasia mostly requires grossing and microscopic examination.

Mutations in KRT10 in epidermolytic acanthoma.

BACKGROUND: Epidermolytic acanthoma (EA) is a rare acquired lesion demonstrating a characteristic histopathological pattern of epidermal degeneration referred to as epidermolytic hyperkeratosis (EHK). On histopathological analysis, EA appears nearly identical to inherited EHK-associated dermatoses such as epidermolytic ichthyosis and ichthyosis bullosa of Siemens. While it has been speculated that EA is caused by mutations in KRT10, KRT1, or KRT2 found in these inherited dermatoses, none have yet been identified. Herein, we aim to identify the contributions of keratin mutations to EA. METHODS: Using genomic DNA extracted from paraffin-embedded samples from departmental archives, we evaluated a discovery cohort using whole-exome sequencing (WES) and assessed remaining samples using Sanger sequencing screening and restriction fragment length polymorphism (RFLP) analysis. RESULTS: DNA from 16/20 cases in our sample was of sufficient quality for polymerase chain reaction amplification. WES of genomic DNA from lesional tissue revealed KRT10 c.466C > T, p.Arg156Cys mutations in 2/3 samples submitted for examination. RFLP analysis of these samples as well as eight additional samples confirmed the mutations identified via WES and identified four additional cases with Arg156 mutations. In sum, 6/11 screened cases showed hotspot mutation in KRT10. CONCLUSIONS: Hotspot mutations in the Arg156 position of KRT10, known to cause epidermolytic ichthyosis, also underlie EA.

Multinucleate cell angiohistiocytoma: A clinicopathologic study of 62 cases and proposed diagnostic criteria.

BACKGROUND: Multinucleate cell angiohistiocytoma (MCAH) is an uncommon and likely underdiagnosed entity that is thought to be of vascular and fibrohistiocytic origin. METHODS: We retrospectively reviewed all cases diagnosed as MCAH at the Yale Medicine Dermatopathology laboratory between 1 January 1990 and 1 September 2018. Sixty-two cases were retained. We performed immunohistochemistry on the ten most inflamed lesions found and assessed for a possible alteration within the Wnt/ß-catenin signaling pathway, involved in follicular induction in dermatofibroma. We subsequently established histologic diagnostic criteria to differentiate MCAH from its mimickers. RESULTS: MCAH affected both genders equally. The hands or fingers were affected in 51.6% of cases. We found the most specific histologic criteria to be: (a) presence of odd multinucleated fibroblasts, (b) presence of superficial parallel fibrosis, (c) presence and thickening of superficial papillary dermal vessels, and (d) absence of perifollicular fibrosis. As for immunoreactivity, we found positivity to CD138, CD163, and CD117 in the mononuclear inflammatory infiltrate. There was no histopathologic evidence of follicular induction, as can be seen in dermatofibromas, and no expression of nuclear beta-catenin as seen in dermatofibromas with follicular induction. CONCLUSION: This large case series establishes MCAH as a distinct clinical and histopathologic entity.

Cutaneous plasmacytosis and multinucleate cell angiohistiocytoma-like lesion in a patient with hepatitis B: A fortuitous triad?

A 28-year-old woman of Chinese descent, with congenital chronic hepatitis B presented with a 7-year history of erythematous-brown papules and plaques on her groins, axillae, and forehead. A first skin biopsy showed findings consistent with two concomitant, yet highly uncommon cutaneous diseases. The presence of lymphoid nodules with germinal centers and clustered polyclonal plasma cells was consistent with cutaneous plasmocytosis. Second, a diffuse proliferation of non-atypical small vessels (CD31+, CD34+, and HHV8-) in a hypercellular stroma peppered with angulated giant cells (CD163+, CD68-) was suggestive of multinucleate cell angiohistiocytoma (MCAH). Interestingly, the second biopsy of a different plaque on the forehead showed only plasmacytosis and the clinical appearance of both plaques and papules alluded to the distinct presence of both concurrent entities. We speculate the immune modulating effects of chronic hepatitis B may have led to a polyclonal plasmacytic proliferation within the dermis. Furthermore, MCAH has been reported in conjunction with other inflammatory skin diseases such as hidradenitis suppurativa and as such we propose that the MCAH lesion in our case may have arisen as a secondary, reactive process to the cutaneous plasmacytosis.

Solitary and multiple epidermolytic acanthoma: A demographic and clinical study of 131 cases.

BACKGROUND: Epidermolytic acanthoma (EA) is a rare, benign acquired cutaneous keratosis displaying epidermolytic hyperkeratosis in more than 50% of its surface. Because of the sparsity of comprehensive studies, little is known on the patient demographics and clinical characteristics of this uncommon entity. We wish to comprehensively characterize the clinical and demographic features of EA and to differentiate it from its mimickers. METHODS: We carried out a retrospective review of 131 cases of EA, recorded clinical and histopathologic features and performed linear regression of yearly incidence rates to assess for possible under-reporting of this entity. RESULTS: EA affected both genders equally. We found 9.08 cases per 100 000 biopsy specimens per year and linear regression analysis showed significantly decreasing incidence rates. Analysis of the anatomical site distribution of EA lesions showed a more frequent genital location in men (39.1% of cases in men, as compared to 11.3% for women). Contrary to previous studies, lesions were most frequently single (91.7%) and the mean age of presentation was 57.8 years. CONCLUSION: The presented largest case series to-date indicates that EA is probably an underdiagnosed entity and establishes the demographic and clinical features of EA.

Hypergranulotic dyscornification: 30 cases of a striking epithelial reaction pattern.

BACKGROUND: Hypergranulotic dyscornification (HD) is a rarely reported histological reaction pattern that may be observed in solitary benign keratoses. OBJECTIVE AND METHODS: We retrospectively reviewed all cases described as displaying "hypergranulotic dyscornification" at our institution between January 1st 1990 to September 1st 2018. We excluded cases that on retrospective review displayed changes of epidermolytic hyperkeratosis. We conducted electron microscopy (EM) of two lesions. RESULTS: Thirty cases were identified in our search. Eleven patients were men and 19 were women. Their mean age was 56.9 ± 21.2 years. In contrast to previous reports, we found that HD does not spare the head and neck area. Frequent clinical impressions were inflamed seborrheic keratosis, Bowen disease or inflamed verruca. The most distinctive histopathologic finding was the presence of a prominent granular layer with clumped perinuclear keratohyaline granules. Some cases had mounds of rounded, anucleate glassy eosinophilic corneocytes in the stratum corneum. We observed one case of incidental HD occurring in an epidermoid cyst. EM of HD showed dense perinuclear bands which appeared to match areas of positive staining by keratin immunohistochemistry, without evidence of pale cytoplasmic areas devoid of keratin filaments, characteristic of epidermolytic hyperkeratosis. CONCLUSION: HD is a reproducible finding in some benign keratoses, probably because of abnormal keratinization. Awareness of this unique reaction pattern will help prevent misdiagnosis.

Hickam's dictum: Angiosarcoma-to-meningioma metastasis.

Tumor-to-tumor metastasis is a seldom reported phenomenon whereby a neoplasm seeds within another histologically distinct tumor, with only 84 cases documented in the literature. We hereby describe the case of a 95-year-old woman who died of widespread metastases identified as a primary hepatic angiosarcoma on autopsy, and the interesting finding of a seeding foci within a dural meningioma. Although meningiomas are the most common intracranial neoplasms to harbor such a phenomenon, this is to our knowledge the first case where an angiosarcoma was identified as the donor tumor.

Incidence, Mortality, and Spatiotemporal Distribution of Cutaneous Malignant Melanoma Cases Across Canada.

BACKGROUND: We recently reported a steady increase in the incidence and mortality of cutaneous malignant melanoma (CMM) in Canada during 1992-2010. OBJECTIVES: The objective of this article is to examine the distribution of Canadian CMM patients at the level of provinces, cities, and forward sortation area (FSA) postal codes. METHODS: Using 3 Canadian population-based registries, we conducted an in-depth examination of the incidence and mortality trends for 72 565 Canadian CMM patients over the period 1992-2010. RESULTS: We found that among 20- to 39-year-olds, the incidence of CMM in women (7.17 per 100 000 individuals) was significantly higher than in men (4.60 per 100 000 individuals per year). Women age 80 years and older had an incidence of CMM (58.46 cases per 100 000 women per year) more than 4 times greater than the national average (12.29 cases per 100 000 population per year) and a corresponding high mortality rate (20.18 deaths per 100 000 women per year), when compared with the Canadian melanoma mortality of 2.4 deaths per 100 000 per year. In other age groups men had higher incidence and corresponding melanoma mortality rates. We also studied CMM incidence by province, city, and FSA postal codes and identified several high-incidence communities that were located near the coast/waterfronts. In addition, plotting latitude measures for cities and FSAs vs CMM incidence rate confirmed the inverse relationship between geographical latitude and incidence of melanoma in Canada (slope = -0.22 ± 0.05). CONCLUSIONS: This research may help develop sex-, age- and geographic region-specific recommendations to decrease the future burden of CMM in Canada.

A Patient With Oral Discomfort and Reduced Oral Aperture.

A patient had burning and pain in the mouth, reduced oral aperture, white-tan plaques on the oral mucosa, and thickened buccal mucosae bilaterally; biopsy of the lower labial mucosa showed subepithelial fibrosis. She had no history of cigarette smoking or use of chewing tobacco but had current and past history of chewing areca nuts. What is the diagnosis and what would you do next?