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Mycobacterium abscessus and M. chelonae belong to the rapid-growing nontuberculous mycobacteria (NTM) group, which are defined by their ability to form visible colonies on agar within 7 days of subculture. Cutaneous infections by this complex show a heterogeneous clinical presentation with varied histopathologic findings. However, the presence of vacuoles in many specimens has been reported as a specific histologic finding. Herein, we correlate the histopathology of patients with tissue-culture positive M. abscessus/M. chelonae complex in order to identify features that may prompt a rapid categorization of the infectious etiology. The cohort includes 33 skin punch biopsy specimens from 28 patients who had associated positive tissue cultures. The most frequent clinical presentation was a single or multiple nodule. Twenty-seven specimens (81.81%) were found to have vacuoles. The observation of certain histologic features (ie, polymorphonuclear microabscesses and epithelioid granuloma formation) should raise the possibility of infection by NTM. In addition to these findings, we believe the presence of vacuoles in the dermal and subcutaneous inflammation should raise suspicion for NTM., (© 2019 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background: Erythema elevatum diutinum (EED) is a rare vasculitis with variable clinical presentation which diagnosis can be challenging. Herein we want to describe the clinicopathological spectrum of findings in five cases of EED., Methods: We retrospectively analyzed five cases in a single institution collected over a period of 27 years. The clinical history was collected and all the slides were examined to determine the histopathological characteristics of the lesions., Results: The mean age of our patients is 56.6 years. Two of five patients were females and with lesions showing predilection for the upper-extremities. The most common presentation was of an erythematous plaque on the extensor surfaces. Three patients had a history of neoplasm. All cases showed leukocytoclastic damage consistent with EED., Conclusion: Our findings suggest that EED shows a heterogeneous clinical and pathological presentation, which can show an overlap with granulomatous dermatoses and mixed connective tissue diseases. Scalp lesions can occur and can mimic granulomatous dermatoses. The finding of EED in benign and malignant solid tumors in three of our patients begs the question whether there is an association between EED and such solid neoplasms., (© 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background: Direct immunofluorescence (DIF) panels (IgG, IgA, IgM, C3 and fibrinogen) are ordered for clinically suspected vasculitis, with frequently negative results., Methods: Cases submitted for DIF and histology (2010-2014) with "vasculitis" in the clinical data were examined, and the electronic medical record reviewed for clinical suspicion of Henoch-Schönlein purpura (HSP). Peri/intravascular IgA was considered positive, other reactants non-specific and no immunoreactivity negative., Results: Vasculitis was the given indication for 20% (258/1318) of DIF studies. HSP was clinically suspected in 36% (95/258). In this setting, leukocytoclastic vasculitis (LCV) was common (66%, 63/95) and DIF was positive in 43% (27/63). One hundred percentage of DIF+ had LCV+. In cases without HSP suspicion, 26% (42/163) were LCV+ and <1% DIF+. Of the 258 cases, LCV+ greatly enriched for DIF+ (105/258 LCV+ with 28/105 [27%] DIF+), captured 100% of HSP and included cases with non-specific DIF/etiologic findings. In LCV cases, DIF positivity was not seen, HSP was not diagnosed and non-specific DIF findings were common., Conclusions: LCV is an H&E-based histopathologic diagnosis that can have positive, negative and non-specific DIF results that are rarely contributory except in the setting of HSP, where DIF is best utilized with IgA as the sole immunoreactant. H&E-based triage of DIF orders is recommended., (© 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background: Angioleiomyoma is a benign neoplasm thought to derive from the tunica media of small venous vessels. Angioleiomyomata most frequently occur in the lower extremities with less common occurrences on the trunk, head and upper extremities. Few cases of acral and digital angioleiomyoma have been described in the literature., Methods: We add a series of 21 patients with acral angioleiomyoma including 6 cases of digital angioleiomyoma to the body of clinical and histological findings along with a review of the literature of digital angioleiomyomata., Results: Digital angioleiomyoma are equally distributed between male and female patients and are more often painful than the angioleiomyoma of all body sites. Acral angioleiomyomata favor the feet over hands at a ratio of 2.5:1, while digital angioleiomyoma favor the fingers over toes at a ratio of 4.3:1., Conclusions: We suggest that vascular leiomyoma be included in the differential diagnosis of smooth muscle tumors with particular regard to the digits of both the hands and the feet. Digital angioleiomyomata differ from acral angioleiomyomata in their equal gender distribution, increased tendency to cause pain and preponderance for the fingers over the toes., (© 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background: Pagetoid Spitz nevus is an uncommon Spitz nevus variant characterized by a predominantly intraepidermal proliferation of single epithelioid melanocytes. Recognition of this variant is important to avoid misdiagnosis as melanoma., Methods: We reviewed and characterized 12 pagetoid Spitz nevi diagnosed at a tertiary care institution over the past 25 years., Results: All patients were female and average age at biopsy was 34 years. Clinically, 83% (10 out of 12) were located on an extremity and all were ≤ 6 mm in diameter. Histologically, pagetoid Spitz nevi were characterized by individual intraepidermal epithelioid melanocytes mostly confined to the lower half of the epidermis. Most displayed epidermal hyperplasia, eosinophilic bodies and melanocytes with minimal pleomorphism. All displayed melanoderma and at least mild dermal inflammation., Conclusions: This represents the largest series of pagetoid Spitz nevi characterized to date. Although most clinicopathologic characteristics in our series correlated with those previously described, novel findings included occurrence in middle-aged adults, occurrence above the waist and demonstration of melanoderma in all lesions. Presence of dermal inflammation and melanoderma may contribute to atypical clinical appearance leading to biopsy despite their small clinical size. Recognition of these additional novel histologic features may aid dermatopathologists in distinguishing pagetoid Spitz nevi from melanoma., (© 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background: Although syphilis is uncommon, infection rates are much higher in HIV-infected individuals than the general population. A proposed explanation is impaired cellular immunity with HIV infection., Methods: A search of one institution yielded 10 patients with a diagnosis of secondary syphilis on skin biopsy, positive syphilis serology and available CD4 counts. We evaluated 11 biopsies from the 10 patients. We correlated the patients' CD4 counts with the histologic findings and with the number of treponemes on skin biopsies, highlighted by immunohistochemistry (IHC). We also compared the detection of spirochetes in silver stained sections (e.g. Warthin-Starry) with T. pallidum IHC. All biopsies were assessed for various histologic features., Results: The sensitivity of IHC to detect treponemes was 64% and of silver stain was 9% (p-value 0.04). The number of treponemes on the biopsies was determined by IHC. High numbers of spirochetes (i.e. >100 per 10 hpf) were only seen in patients with CD4 counts less than 250 cells/ml., Conclusion: The most consistent histologic finding was a moderate to severe lymphoplasmacytic infiltrate. Although the study is small, it appears that a higher number of spirochetes is associated with CD4 counts less than 250 cell/ml. The T. pallidum IHC stain was vastly superior to the Warthin-Starry stain., (© 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

The differential diagnosis for eosinophil-rich skin lesions often includes a drug reaction, allergic contact dermatitis and rarely, response to a helminth infection. However, many unrelated entities, such as infections, neoplasms and inflammatory dermatoses, can have a prominent eosinophilic infiltrate. Syphilis is classically associated with plasma cells, but other patterns of inflammation have been reported, including ulcerative, granulomatous and eosinophil-rich. Classic teaching might indicate that the presence of eosinophils argues against a diagnosis of syphilis. We present four cases of secondary syphilis with increased eosinophils, ranging from 8 to >200 eosinophils per 10 high-power fields (×400 magnification). Patient 1 had lesions on the penis and scrotum, with greater than 200 eosinophils per 10 high-power fields. Patient 2 had lesions on the back, with 150 eosinophils per 10 high-power fields. Patient 3 had lesions on the bilateral arms, with 8 eosinophils per 10 high-power fields. Patient 4 had lesions involving the anus, with 17 eosinophils per 10 high-power fields. These cases highlight that the presence of an eosinophil-rich infiltrate on skin biopsy should not exclude syphilis from the differential diagnosis., (© 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

A neutrophil-predominant inflammatory infiltrate in a cutaneous biopsy can be associated with a broad spectrum of diseases. Here we describe three cases showing a neutrophil-predominant dermal infiltrate admixed with abundant acellular bodies surrounded by capsule-like vacuolated spaces, which strikingly mimicked Cryptococcus. Two cases occurred within the settings of underlying hematologic malignancies; the third case was associated with immune dysregulation. Two patients were acutely ill in the medical intensive care unit. Fungal work-up, including cultures and multiple stains were negative. Because of clinical deterioration in these patients, transmission electron microscopy was pursued to definitively rule out fungal infection. In both cases, characteristics most compatible with autolysing human cells, not Cryptococcus, were identified. Chemotherapy and high-dose steroids were given, but both patients eventually succumbed to their diseases. To the best of our knowledge, these represent the first reported cases of autolysing human cells mimicking Cryptococcus organisms within neutrophilic infiltrates. They highlight the therapeutic dilemmas arising with histopathologic mimics, as well as the importance of thorough investigation to distinguish mimickers from true infectious organisms. We believe recognition of this microscopic pitfall will be useful to dermatopathologists faced with similar findings in the future, and may prevent unnecessary delay of appropriate therapy in acutely ill patients., (Copyright © 2012 John Wiley & Sons A/S.)

Background: Perineurioma is a rare benign soft-tissue tumor composed of cells showing differentiation toward the perineurial cells of the nerve sheath. Although mutations in the neurofibromatosis 2 (NF2) gene have been documented in this tumor, there is no known association between perineuriomas and type 1 or 2 NF., Methods: This is the first report of a case of soft-tissue perineurioma occurring in a patient with NF1., Results: Histopathologic examination revealed a 2.0-cm well-circumscribed, spindle-cell neoplasm with slender, elongated, bipolar, wavy cytoplasmic processes and wavy, elongated nuclei in a hyalinized stroma with focal myxoid areas. The architecture was composed predominantly of short fascicles with areas exhibiting a storiform pattern. Immunohistochemistry showed positive labeling for epithelial membrane antigen (EMA) but no staining for S-100 and smooth muscle actin (SMA)., Conclusion: This case illustrates that perineurioma can occur in association with NF1. Perineuriomas can be confused with other spindle-cell neoplasms, and relevant features and immunohistochemistry of these lesions are outlined. The patient has not had a recurrence with limited follow-up.