Diagnostic Accuracy of Virtual Pathology vs Traditional Microscopy in a Large Dermatopathology Study.

Importance: Digital pathology represents a transformative technology that impacts dermatologists and dermatopathologists from residency to academic and private practice. Two concerns are accuracy of interpretation from whole-slide images (WSI) and effect on workflow. Studies of considerably large series involving single-organ systems are lacking. Objective: To evaluate whether diagnosis from WSI on a digital microscope is inferior to diagnosis of glass slides from traditional microscopy (TM) in a large cohort of dermatopathology cases with attention on image resolution, specifically eosinophils in inflammatory cases and mitotic figures in melanomas, and to measure the workflow efficiency of WSI compared with TM. Design, Setting, and Participants: Three dermatopathologists established interobserver ground truth consensus (GTC) diagnosis for 499 previously diagnosed cases proportionally representing the spectrum of diagnoses seen in the laboratory. Cases were distributed to 3 different dermatopathologists who diagnosed by WSI and TM with a minimum 30-day washout between methodologies. Intraobserver WSI/TM diagnoses were compared, followed by interobserver comparison with GTC. Concordance, major discrepancies, and minor discrepancies were calculated and analyzed by paired noninferiority testing. We also measured pathologists' read rates to evaluate workflow efficiency between WSI and TM. This retrospective study was caried out in an independent, national, university-affiliated dermatopathology laboratory. Main Outcomes and Measures: Intraobserver concordance of diagnoses between WSI and TM methods and interobserver variance from GTC, following College of American Pathology guidelines. Results: Mean intraobserver concordance between WSI and TM was 94%. Mean interobserver concordance was 94% for WSI and GTC and 94% for TM and GTC. Mean interobserver concordance between WSI, TM, and GTC was 91%. Diagnoses from WSI were noninferior to those from TM. Whole-slide image read rates were commensurate with WSI experience, achieving parity with TM by the most experienced user. Conclusions and Relevance: Diagnosis from WSI was found equivalent to diagnosis from glass slides using TM in this statistically powerful study of 499 dermatopathology cases. This study supports the viability of WSI for primary diagnosis in the clinical setting.

Multifocal, fixed-drug eruption masquerading as recurrent erythema multiforme.

Fixed drug eruptions often have a characteristic appearance, which, when correlated with the clinical history, can be easily identified. However, multifocal fixed drug eruptions, especially the non-pigmenting variety, can present a diagnostic challenge, especially in the absence of a complete medication history. We present such a case, in which the patient was taking two over-the-counter medications, both of which contain uncommon causes of multifocal fixed drug eruptions.

Pruritic rash on trunk.

The patient had been treated with topical antifungals and steroids without relief, but a more detailed history suggested a serious infectious etiology.

Low-grade myxofibrosarcoma presenting at the site of prior high-grade disease.

Myxofibrosarcoma is one of the most common soft tissue sarcomas occurring in older adults. It can arise de novo or can be radiation induced, and the term myxofibrosarcoma was originally devised to encompass a spectrum of myxoid tumors with characteristics similar to malignant fibrous histiocytoma (MFH). Confusion exists, however, regarding the distinction between microscopic grade and characteristics of myxofibrosarcoma and MFH. Correct classification is vital to prognosis, as the degree of myxoid change is inversely related to the incidence of metastasis. We present a case of a 76-year-old man with a history of high-grade MFH of the left lower extremity, status post excision and radiation therapy, who presented 2 years later with a regional metastatic recurrence of high-grade MFH to the left groin as well as new nodules adjacent to and within his prior excision and radiation site. These new nodules were determined to represent low-grade myxofibrosarcoma. These new low-grade lesions either represent a low-grade recurrence of high-grade sarcoma or a new, radiation-induced soft tissue sarcoma occurring at the same site. Radiotherapy, however, is an unlikely cause; specific postradiation sarcoma criteria have not been fulfilled. This article discusses both the nosology and histopathological spectrum of these important soft tissue sarcomas, their aggressive and recurrent nature and their association with radiation therapy.

Permanent press allergy in an active duty U.S. Army soldier.

Ethylene urea/melamine formaldehyde resin (permanent press) is a common fabric finishing agent added to Army Combat Uniforms for a wrinkle-free appearance and to strengthen the fabric. We describe the case of an active duty U.S. Army soldier with a diffuse eczematous dermatitis in whom patch testing was used to identify an allergy to permanent press, a ubiquitous fabric finishing agent in the Army combat uniform. To our knowledge, this is the first case report of a soldier with an allergic contact dermatitis to ethylene urea/melamine formaldehyde resin. This case highlights the importance of considering the diagnosis of allergic contact dermatitis in patients with a recurrent eczematous dermatitis that does not respond appropriately to therapy and the unique occupational impact of diagnosing an Army soldier with permanent press allergy.

Papular pityriasis rosea.

Pityriasis rosea (PR) is a seasonal papulosquamous disorder that can be easily confused with a wide variety of similar appearing cutaneous disorders. This is particularly evident in its atypical papular form. We present a case report of atypical papular PR, along with a discussion of clinical presentation, histologic criteria, proposed etiology, and treatment options. Papular PR is atypical, presenting in a minority of patients, and may pose a diagnostic challenge. Being familiar with these atypical characteristics will facilitate accurate and timely diagnosis.