Fusion-driven cutaneous and superficial mesenchymal and adnexal tumors-A clinicopathologic and molecular study of 15 cases, including a novel case of ACTB::ZMIZ2-rearranged adnexal carcinoma.

BACKGROUND: While the list of fusion-driven soft tissue neoplasms is expanding rapidly, their importance among cutaneous and superficial mesenchymal and adnexal neoplasms remains poorly understood. This challenge is especially evident in cases with ambiguous histopathology that are difficult to classify based on morphology. AIMS: Our goal was to investigate the benefits of next-generation sequencing in diagnosing complex cutaneous neoplasms. MATERIALS & METHODS: Departmental archives were searched for fusion-driven cutaneous neoplasms. Slides were retrieved and clinical information including follow-up was obtained. RESULTS: Fifteen cases occurred in eight female and seven male patients, with a median age of 26 years (range: 1-83) at diagnosis. Tumors involved the extremities (9), scalp (5), and head and neck (1). Predominant features included myoepithelial (5), nested spindled with clear cytoplasm (2), atypical adnexal/squamoid (2), small round blue cell (2), cellular spindled (3), and fibrohistiocytic morphology (1). Most frequently encountered fusions involved EWSR1 (6) fused to ERG (1), FLI1 (1), CREB1 (2), CREM (1), PBX3 (1), followed by PLAG1 (4) with LIFR (2), TRPS1 (1) and CHCHD7. Additional fusions encountered were YAP1::NUTM1, EML4::ALK, SS18::SSX1 (2), and a novel fusion: ACTB::ZMIZ2. Integration of histologic features and molecular findings led to final diagnoses of primary cutaneous Ewing sarcoma (2), soft tissue myoepithelioma (4), cutaneous syncytial myoepithelioma (1), cutaneous adnexal carcinoma (1), porocarcinoma (1), inflammatory myofibroblastic tumor (1), synovial sarcoma (2), clear cell sarcoma (2), and angiomatoid fibrous histiocytoma (1). DISCUSSION AND CONCLUSION: Our results show that fusion testing can be a helpful diagnostic tool, especially in cases with unusual or uncommon morphology in superficial sites. Furthermore, it can allow for the identification of potential therapeutic targets in some instances.

Comparison of Digital Pathology and Light Microscopy Among Dermatology Residents: A Reappraisal Following Practice Changes.

BACKGROUND: Following transition to digital pathology for primary diagnosis at our institution, dermatology residents have reduced exposure to light microscopy. This study compares resident competency with light microscopy versus digital pathology following practice changes. METHODS: Twenty-one dermatology residents were administered a dermatopathology examination composed of 32 diagnoses evaluated using digital slides and 32 with light microscopy. Case difficulty was graded and balanced between modalities. Diagnostic accuracy was measured using the number of correct diagnoses for each modality. Participants were surveyed regarding their experience and preferences. RESULTS: Diagnostic accuracy was higher with digital pathology than light microscopy (22/32 vs. 18/32, P < 0.001). Diagnostic accuracy with digital pathology increased with years of training, but accuracy with light microscopy did not. Residents with previous light microscopy experience achieved an average score of 19/32 on glass, as compared with 10/32 for those without experience (P = 0.039). Digital pathology was preferred over light microscopy (18/21, 85.7%). CONCLUSIONS: Trainees had better diagnostic proficiency with digital pathology and preferred this modality. Most practices at this time continue to use light microscopy. Therefore, we need to maintain proficiency in microscopy during training while concurrently preparing trainees for a digital future.

Histopathologic features predictive of perivascular deposition of IgA on direct immunofluorescence in cases of leukocytoclastic vasculitis: A retrospective study of 112 specimens.

IgA vasculitis is a small-vessel vasculitis subtype with increased risk of systemic involvement. We aimed to investigate if any light-microscopic features can predict the presence of perivascular granular IgA deposits on direct immunofluorescence (DIF) microscopy. We performed a retrospective search of cutaneous pathology reports from our internal and consultation practice (January 1, 2010-October 5, 2021) with a diagnosis of leukocytoclastic vasculitis and accompanying DIF. A blinded dermatopathologist reviewed standard microscopy slides for predetermined histopathological features. Fifty-six biopsies (48 patients) and 56 biopsies (42 patients) met inclusion criteria for IgA+ and IgA-, respectively. The presence of eosinophils and mid and deep dermal inflammation were statistically more associated with IgA- (41/56 [73.2%] and 31/56 [55.4%], respectively) than IgA+ cases (28/56 [50.0%] and 14/56 [25.0%]; p = 0.049 and 0.006, respectively, chi-squared test). Other microscopic criteria recorded were not significantly different between the two groups (p > 0.05, chi-squared and Fisher's exact tests). In this retrospective study of 112 cases, we found that while the absence of eosinophils and absence of mid- and deep inflammation were correlated with increased likelihood of IgA perivascular deposition on DIF, no other histopathological features on light microscopy tested could reliably predict the presence of IgA perivascular deposition on DIF. Therefore, DIF remains a necessary component for the accurate diagnosis of cutaneous IgA vasculitis.

Impact of adding an IgG4 conjugate to routine direct immunofluorescence testing for subepithelial and intraepithelial autoimmune blistering disorders.

BACKGROUND: Certain autoimmune bullous dermatoses are mediated by autoantibodies of the IgG4 subclass. We determined the diagnostic impact of adding IgG4 to our conventional direct immunofluorescence (DIF) panel. METHODS: For all cases submitted to our referral laboratory for DIF over 1 month (n = 630), we performed IgG4 testing and collected consecutive biopsy specimens showing definite or indeterminate linear or cell-surface deposition of IgG, IgG4, and/or C3. On retrospective blinded review, we classified the pattern and whether the findings were definite, indeterminate, or negative. When present, substantial background staining was recorded. RESULTS: Seventy DIF specimens met the inclusion criteria. Of 22 (31.4%) specimens equivocal for linear or cell-surface deposition, 9 (40.9%) had definitive IgG4 findings, either linear (3 of 14 equivocal linear cases; 21.4%) or cell-surface (6 of 8 equivocal cell-surface cases; 75.0%). Background deposition was substantial in 14 cases (20.0%) for IgG but in none for C3 or IgG4. CONCLUSION: IgG4 allowed the classification of over 40% of DIF cases that were otherwise equivocal by IgG and C3. IgG4 staining showed lower levels of non-specific background staining than IgG or C3. IgG4 appears to contribute most value in cases with cell-surface deposition or with equivocal linear IgG deposition and negative C3 results.

Community-Based Study of Celiac Disease Autoimmunity Progression in Adults.

BACKGROUND & AIMS: Celiac disease can develop at any age, but outcomes of adults with positive results from serologic tests for tissue transglutaminase antibodies (tTGA) without endoscopic determination of celiac disease (called celiac autoimmunity) have not been thoroughly evaluated. We investigated the proportion of adults with celiac autoimmunity at a community medical center and their progression to celiac disease. METHODS: We analyzed waste blood samples from a community clinic from 15,551 adults for tTGA and, if titer results were above 2 U/mL, for endomysial antibody. The blood samples had been collected at 2 time points (median interval, 8.8 years) from 2006 through 2017. We collected data from the clinic on diagnoses of celiac disease based on duodenal biopsy analysis. RESULTS: Of the serum samples collected at the first time point, 15,398 had negative results for tTGA, and 153 had positive results for tTGA (>4 U/mL). Based on medical records, 6 individuals received a diagnosis of celiac disease, for a cumulative incidence of celiac disease diagnosis of 0.06% (95% confidence interval, 0.01-0.11). Forty-nine (0.32%) individuals with a negative result from the first serologic test for tTGA had a positive result from the second test. Among the 153 adults who were tTGA positive at the first time point, 31 (20%) had a subsequent diagnosis of celiac disease, 81 (53%) remained positive for tTGA without a clinical diagnosis of celiac disease, and 41 (27%) had negative test results for tTGA at the second time point. Higher initial tTGA titers, female sex, and a history of hypothyroidism and autoimmune disease were associated with increased risks of subsequent diagnosis of celiac disease. Interestingly, adults whose first blood sample had a positive test result but second blood sample had a negative result for tTGA were older, had lower-than-average initial tTGA titer results, and had a higher mean body mass index than adults whose blood samples were positive for tTGA at both time points and adults later diagnosed with celiac disease. CONCLUSIONS: In an analysis of serum samples collected from a community clinic an average of 8.8 years apart, we found that fewer than 1% of adults with negative results from an initial test for tTGA have a positive result on a second test. Of adults with positive results from the test for tTGA, only 20% are later diagnosed with celiac disease; the remaining individuals maintain persistent increases in tTGA without diagnoses of celiac disease or have negative results from second tests.

Subepithelial autoimmune bullous dermatoses disease activity assessment and therapy.

Subepidermal (subepithelial) autoimmune blistering dermatoses are a group of rare skin disorders characterized by the disruption of the dermal-epidermal junction through the action of autoantibodies. The fourth article in this continuing medical education series presents the current validated disease activity scoring systems, serologic parameters, treatments, and clinical trials for bullous pemphigoid, mucous membrane pemphigoid, epidermolysis bullosa acquisita, bullous systemic lupus erythematosus, anti-p200 pemphigoid, linear IgA bullous dermatosis, and dermatitis herpetiformis.

Subepithelial autoimmune blistering dermatoses: Clinical features and diagnosis.

Subepithelial autoimmune blistering dermatoses are a group of rare skin disorders that are characterized by the disruption of the dermal-epidermal junction through the action of autoantibodies. The third article in this continuing medical education series explores the background, epidemiology, clinical features, and diagnostic criteria of each of the major subepithelial autoimmune blistering dermatoses, including bullous pemphigoid, pemphigoid gestationis, lichen planus pemphigoides, mucous membrane pemphigoid, linear IgA bullous dermatosis, and dermatitis herpetiformis.

Intraepithelial autoimmune blistering dermatoses: Clinical features and diagnosis.

Intraepithelial autoimmune blistering dermatoses are a rare group of skin disorders characterized by the intraepithelial disruption of intercellular connections through the action of autoantibodies. The first article in this continuing medical education series explores the background, epidemiology, clinical features, and diagnostic criteria of each of the major intraepithelial autoimmune blistering dermatoses, including pemphigus foliaceus, pemphigus erythematosus, pemphigus herpetiformis, fogo selvagem, pemphigus vulgaris, pemphigus vegetans, drug-induced pemphigus, IgA pemphigus, IgG/IgA pemphigus, and paraneoplastic pemphigus/paraneoplastic autoimmune multiorgan syndrome.

Intraepithelial autoimmune bullous dermatoses disease activity assessment and therapy.

Intraepithelial autoimmune blistering dermatoses are a rare group of skin disorders characterized by disruptions of inter-keratinocyte connections within the epidermis through the action of autoantibodies. The second article in this continuing medical education series presents validated disease activity scoring systems, serologic parameters of disease, treatments, and clinical trials for pemphigus and its subtypes.

Kaposi sarcoma misdiagnosed as granuloma annulare: A case of mistaken identity.

The microscopic features of patch stage Kaposi sarcoma (KS) and interstitial granuloma annulare (GA) may be difficult to differentiate, because both may exhibit a subtle "busy" dermis due to infiltration of spindled cells between collagen bundles. The clinical distinction is particularly challenging in human immunodeficiency virus (HIV)-affected individuals, as the incidence of GA appears to be greater in the HIV-infected population. KS is the most common neoplasm in this population. Despite the significant decrease in the incidence of KS since the advent of highly active antiretroviral therapy (HAART), KS tends to occur with late onset and indolent progression in patients with preserved immune function and minimal viral load. We present a 47-year-old homosexual HIV-positive man, under virologic and immunologic control on long-term HAART therapy, with a 5-year history of progressive red-brown patches and plaques on the legs, feet, hands, and trunk. Prior skin biopsy specimens were interpreted as interstitial GA. Histopathology on new skin biopsy specimens along with review specimens supported the diagnosis of plaque and patch stages of KS, respectively, supported by immunohistochemical expression of human herpes virus-8 (HHV-8). This case underscores the importance of maintaining a high suspicion for KS in progressive, treatment-recalcitrant skin lesions, particularly in HIV-infected individuals.

Pyoderma gangrenosum in hematologic malignancies: A systematic review.

BACKGROUND: Pyoderma gangrenosum (PG) is a devastating neutrophilic dermatosis that may be associated with trauma or systemic diseases. The associations, characteristics, and temporal relationship of PG with hematologic malignancies are not well understood. OBJECTIVE: We performed a systematic review of PG associated with hematologic malignancies using data from case reports, case series, and retrospective studies. METHODS: We searched MEDLINE, EMBASE, Scopus, and Web of Science from each database's inception to December 12, 2018. Two reviewers independently selected studies and extracted data. RESULTS: Two hundred seventy-nine publications met the inclusion criteria (340 cases). Myelodysplastic syndrome (MDS) was the most commonly reported hematologic malignancy associated with PG, followed by monoclonal gammopathy of undetermined significance and acute myeloid leukemia. The mean age of patients was 56.5 years, with males being more common. There was a predominance of the ulcerative PG subtype and multifocal distributions across all hematologic malignancies. The majority of MDS cases preceded PG, which was reversed for MGUS. LIMITATIONS: The data were limited by reporting bias because PG subtypes rely on the rendered diagnosis reported. In addition, the classification for hematologic malignancies has evolved since 1978. CONCLUSION: Patients with PG should be evaluated for hematologic malignancies, with MDS being the most common.

Circulating bullous pemphigoid autoantibodies in the setting of negative direct immunofluorescence findings for bullous pemphigoid: A single-center retrospective review.

BACKGROUND: Bullous pemphigoid (BP) autoantibody levels are generally elevated in patients with BP but can be present nonspecifically in patients without BP. OBJECTIVE: To analyze the clinical findings of patients with elevated BP180 or BP230 autoantibody levels and negative direct immunofluorescence (DIF) study findings. METHODS: We retrospectively reviewed records of patients seen at our institution during January 1, 2005-December 31, 2015, who were positive for BP180 or BP230 autoantibodies and had a negative DIF study finding. These patients' demographic characteristics and BP180 and BP230 levels were compared with those of a BP control group who were positive for BP180 or BP230 autoantibodies and had positive DIF study findings. RESULTS: We identified 208 patients with BP autoantibodies but without positive DIF study findings. These patients' mean age and enzyme-linked immunosorbent assay values were significantly lower than those of the control group. Dermatitis was the most common final clinical diagnosis. Of the 208 patients, 41 (19.7%) had at least 2 years' follow-up. Four patients had positive DIF results upon repeating the test and ultimately received pemphigoid diagnoses. LIMITATIONS: Retrospective design with limited follow-up. CONCLUSION: Patients might harbor serum BP autoantibodies in the context of a wide range of dermatoses. Low positive BP180 and BP230 autoantibody levels should not be overinterpreted as evidence for BP in the setting of a negative DIF.

Prevalence and Morbidity of Undiagnosed Celiac Disease From a Community-Based Study.

BACKGROUND & AIMS: Little is known about the prevalence and burden of undiagnosed celiac disease in individuals younger than age 50. We determined the prevalence and morbidity of undiagnosed celiac disease in individuals younger than age 50 in a community. METHODS: We tested sera from 31,255 residents of Olmsted County, Minnesota (<50 y), without a prior diagnosis of celiac disease assay using an assay for IgA against tissue transglutaminase; in subjects with positive test results, celiac disease was confirmed using an assay for endomysial IgA. We performed a nested case-control study to compare the proportion of comorbidities between undiagnosed cases of celiac disease and age- and sex-matched seronegative controls (1:2). Medical records were abstracted to identify potential comorbidities. RESULTS: We identified 338 of 30,425 adults with positive results from both serologic tests. Based on this finding, we estimated the prevalence of celiac disease to be 1.1% (95% confidence interval, 1.0%-1.2%); 8 of 830 children tested positive for IgA against tissue transglutaminase (1.0%; 95% confidence interval, 0.4%-1.9%). No typical symptoms or classic consequences of diagnosed celiac disease (diarrhea, anemia, or fracture) were associated with undiagnosed celiac disease. Undiagnosed celiac disease was associated with increased rates of hypothyroidism (odds ratio, 2.2; P < .01) and a lower than average cholesterol level (P = .03) and ferritin level (P = .01). During a median follow-up period of 6.3 years, the cumulative incidence of a subsequent diagnosis with celiac disease at 5 years after testing was 10.8% in persons with undiagnosed celiac disease vs 0.1% in seronegative persons (P < .01). Celiac disease status was not associated with overall survival. CONCLUSIONS: Based on serologic tests of a community population for celiac disease, we estimated the prevalence of undiagnosed celiac disease to be 1.1%. Undiagnosed celiac disease appeared to be clinically silent and remained undetected, but long-term outcomes have not been determined.

Frontal fibrosing alopecia among men: A clinicopathologic study of 7 cases.

BACKGROUND: Frontal fibrosing alopecia (FFA) is a lichen planopilaris-variant scarring alopecia that has rarely been described in men. OBJECTIVE: To characterize the clinicopathologic findings of FFA in men by studying a series of 7 male patients. METHODS: We conducted a retrospective review of all cases of male patients with FFA at the Mayo Clinic from 1992 to 2016. RESULTS: Seven male patients with FFA were identified. The frontal scalp (in 6 of 7 patients), sideburns (in 4 of 7), and temporal scalp (in 4 of 7) were most frequently involved. Three patients had involvement of the eyebrows. One patient had hair loss of the upper cutaneous lip. All patients had biopsy evidence of lichen planopilaris. None of the patients had associated autoimmune or thyroid disease. Two patients had hypogonadism upon testosterone studies. LIMITATIONS: Limitations include small sample size and varied follow-up. CONCLUSIONS: Although most often reported among postmenopausal women, FFA also occurs among men. The clinical and histopathologic characteristics of FFA in men parallel those described in women with FFA. Unique areas of involvement in men include sideburns and facial hair. Concomitant mucocutaneous lichen planus, autoimmune disease, and thyroid disease are infrequent among men with FFA. Distribution of hair loss and associated hormonal abnormalities aid in the recognition of FFA in men.

Amicrobial pustulosis of the folds: Report of 4 cases.

Amicrobial pustulosis of the folds (APF) is a rare disease characterized by aseptic pustular lesions involving cutaneous folds, typically occurring in the context of an autoimmune disorder. We present 4 patients with APF, focusing on clinical and histopathologic characteristics to improve the recognition of this entity. All 4 patients had intertriginous and extra-intertriginous involvement. Common histopathologic features of skin biopsies in these patients were intracorneal, subcorneal, intraepidermal, perivascular, perifollicular and interstitial neutrophilic inflammation. Pustules overlying adnexal ostium and papillary dermal edema were consistently observed. The pustules were negative for microorganisms on stain testing. In these cases, associated conditions were undifferentiated connective tissue disease, systemic lupus erythematosus, antiphospholipid syndrome, Crohn disease and Hashimoto thyroiditis. The aforementioned clinical and histopathologic characteristics of patients with suspected or diagnosed connective tissue disorders should lead to suspicion for APF.

Pyostomatitis vegetans (PSV)-pyodermatitis vegetans (PDV): A clinicopathologic study of 7 cases at a tertiary referral center.

BACKGROUND: Pyostomatitis vegetans (PSV)-pyodermatitis vegetans (PDV) is a rare inflammatory mucocutaneous disease associated with inflammatory bowel disease. OBJECTIVE: We sought to evaluate the clinicopathologic findings of PSV-PDV in a series of 7 patients. METHODS: We conducted a retrospective review of all cases of PSV-PDV at the Mayo Clinic from 1995 to 2014. RESULTS: Seven patients with PSV-PDV were included, and all had inflammatory bowel disease. Three had Crohn's disease and 4 had ulcerative colitis. Three patients had peripheral blood eosinophilia. Two had concomitant pyoderma gangrenosum in which pyoderma gangrenosum lesions were recalcitrant to therapy. Primary sclerosing cholangitis was seen in 3 patients. Two patients had direct and 3 had indirect immunofluorescence findings. Tissue eosinophilia was seen in the majority of mucosal and cutaneous lesions. LIMITATIONS: Limited sample size and retrospective study design are limitations. CONCLUSIONS: PSV-PDV is associated with inflammatory bowel disease and primary sclerosing cholangitis and may precede gastrointestinal symptoms. Immunofluorescence findings in select PSV-PDV cases may indicate possible overlap with autoimmune bullous disease. Tissue eosinophilia may be helpful in distinguishing PSV-PDV from pyoderma gangrenosum. Strict control of bowel disease and close monitoring of patients with subclinical disease is warranted.