Gibson, Lawrence E.

AbstractBackgroundUnderstanding whether specific histopathologic features on skin biopsy are predictive of systemic associations in dermatomyositis (DM) would be useful to guide clinical screening.MethodsThrough retrospective medical record search, clinical and laboratory findings of patients with DM were documented. Existing skin biopsy slides were re‐reviewed blindly.ResultsOf all biopsy specimens (n = 42), the most frequent histopathological finding was vacuolar interface dermatitis (95%). Other features included perivascular lymphocytic infiltrate (71%), increased dermal mucin (40%), vessel wall thickening (12%), follicular plugging (9.5%), and dermal sclerosis (7%). Neutrophilic infiltrate was observed in three biopsies from a patient with adalimumab‐associated DM. Vasculitis was not observed. There was no statistically significant difference in the presence of any histopathological feature and that of various systemic manifestations (i.e., myopathy, interstitial lung disease [ILD] and malignancy). However, we observed that dense lichenoid infiltrate rather than pauci‐inflammatory changes correlated with severe itching (p < 0.001). Patients with MDA‐5 antibodies were significantly more likely to have vasculopathy than those without (p = 0.029*).ConclusionsNo dermatopathologic feature was reliably predictive of myopathy, ILD, or malignancy. This finding implies that, regardless of histopathologic findings, patients should be screened for associated conditions as clinically indicated.

AbstractBackgroundCertain 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.MethodsFor 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.ResultsSeventy 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.ConclusionIgG4 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.

AbstractBackgroundIntravascular histiocytosis is an underrecognized reactive skin condition characterized by the clinical finding of poorly demarcated erythematous to violaceous patches and plaques. The diagnosis is confirmed by the histologic findings of intraluminal histiocytes on skin biopsy and exclusion of an alternative diagnosis.MethodsA review of patients with a histologic diagnosis of intravascular or intralymphatic histiocytosis and seen at Mayo Clinic, Rochester, Minnesota, from January 1, 2010, to October 10, 2020, was performed. Histologic and clinical information was collected from the medical records.ResultsNine patients were identified. Clinical impressions prior to biopsy varied widely, and no clinician included intravascular histiocytosis in the initial clinical differential diagnosis. Eight patients had preceding trauma to the affected area.ConclusionIntravascular histiocytosis remains a rare skin condition. Clinical identification remains low. Our cases add support to the hypothesis that intravascular histiocytosis is a reactive condition often preceded by trauma and/or surgery.

AbstractBackgroundThe purpose of this study was to retrospectively assess clinical characteristics and mortality rate of Stevens–Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) in patients who developed disseminated intravascular coagulation (DIC).MethodsA systematic retrospective chart review of all patients with concurrent clinical diagnosis of DIC and SJS/TEN between July 1, 2012, and January 1, 2020, at the Mayo Clinic was performed.ResultsThe incidence of DIC in patients with SJS/TEN was 1.3% at our institution (5 of 396 DIC patients). Triggers of SJS/TEN included lamotrigine, clofarabine, antibiotics, and sepsis. Two patients diagnosed with SJS and two patients with TEN succumbed to the disease.ConclusionDIC is a rare underlying risk in patients with SJS/TEN and is associated with increased mortality. Early clinician awareness and aggressive intervention is advised.

AbstractBackgroundMycosis fungoides (MF) is characterized by epidermotropic atypical lymphocytes in the absence of spongiosis. However, we describe an unusual presentation of MF with spongiosis, mimicking benign inflammatory dermatoses and highlight the importance of pathologic interpretation for diagnostic confirmation.MethodsA cross‐sectional study of consecutive patients diagnosed with MF with spongiosis was conducted. The clinical, histopathologic, immunophenotypic, and molecular genetic features of cases were reviewed.ResultsWe identified nine cases of MF (age range 34‐82 years; mean 75 years), with an initial diagnosis of dermatitis (6/9), psoriasis (4/9), or other inflammatory dermatoses (2/9). Pruritus, pain, and blisters were common clinical manifestations. The most common areas of involvement were the extremities (8/9). Epidermotropism with spongiosis was a central histopathological feature in all cases.ConclusionThese cases highlight prominent spongiosis in MF and overlap with common benign inflammatory dermatoses. We present these cases to show the diagnostic pitfalls associated with spongiotic presentations of MF. Dermatitis, psoriasis, and other inflammatory skin conditions not responsive to standard therapy warrant further work‐up including biopsy to rule out MF. Multiple skin biopsies and review by a dermatopathologist with expertise in the diagnosis of cutaneous lymphoma is highly recommended.

SummaryBackgroundAlpha‐1 antitrypsin deficiency (AATD) may be associated with liver and lung disease and rarely causes panniculitis.ObjectiveWe evaluated the clinicopathologic and laboratory findings of AATD panniculitis in 10 patients.MethodsWe conducted a retrospective review of all cases of AATD panniculitis at Mayo Clinic, Rochester, MN, from 1989 to 2016.ResultsTen patients with AATD panniculitis were included. Seven of ten were women. Clinical lesions were most commonly nodular (100%), erythematous (90%), ulcerated (90%), and painful (90%) subcutaneous nodules and plaques. Extracutaneous associations were rare. PiZZ phenotype was most commonly identified (50%). Histopathologically, lobular panniculitis (80%) with associated septal involvement (60%) and a predominant neutrophilic infiltrate (100%) were most common. Treatments varied; dapsone and alpha‐1 proteinase inhibitor infusions were each used in five (50%) patients, respectively. In patients with greater than 6‐month follow‐up (n = 4), one patient continued to have disease activity despite treatment.ConclusionAATD panniculitis should be considered in the differential for a painful, ulcerative panniculitis with a predominantly neutrophilic histopathologic infiltrate. Diagnosis can be made with clinicopathologic correlation and genetic and laboratory evaluations. Serum AAT level and phenotype assists in diagnosing patients with suspected AATD panniculitis.

Abstract: Vascular tumors in infants present a diagnostic and treatment dilemma for both clinicians and pathologists. Infantile hemangioma, the most common vascular tumor in infants, can be confused for other less common vascular tumors in infants. Correct and timely diagnosis is important, as some vascular tumors can be associated with life-threatening coagulopathy. We present the cases of 5 vascular tumors that have clinical and histologic overlap: infantile hemangioma, pyogenic granuloma, noninvoluting congenital hemangioma, tufted angioma, and kaposiform hemangioendothelioma. Typical clinical and histopathologic features of each lesion are summarized. We review the utility and characteristic immunohistochemistry including CD31, CD34, GLUT-1, D2-40, LYVE-1, Prox-1, and WT-1. Collaboration between the clinician and the dermatopathologist correlating the clinical history and histopathologic features can lead to the correct diagnosis, whereas the utility of immunohistochemistry remains in question.