American Journal of Dermatopathology最新文献

Abstract: Primary cutaneous amoebiasis is rare, and typically affects immunocompromised patients and presents with unique clinical and histopathologic changes. Untreated, the infection could progress to involve the central nervous system, which is almost universally fatal. We present a case of primary cutaneous acanthamoebiasis in a patient with chronic lymphocytic leukemia on acalabrutinib. Timely diagnosis and treatment resulted in complete resolution of lesions and a disease-free status at the 14-month follow-up. A 76-year-old man presented with a 2-month history of multiple, nonhealing, ulcerated, erythematous, painful, crusted nodules on his trunk, and upper and lower extremities. Two punch biopsies showed mixed inflammatory infiltrate with a histiocytic reaction and microabscesses extending into the deep dermis. Rare, unusual structures with cytoplasmic vacuolations and round nuclei were seen on repeated biopsies. Gomori methenamine silver delineated wrinkled double-walled cytoplasm of rare parasites, concerning for amoebic infection. Molecular workup (polymerase chain reaction) came back positive for Acanthamoeba castellanii . Initial treatment involved flucytosine and fluconazole, followed by fluconazole and miltefosine, but both were discontinued because of nausea and replaced with single-agent voriconazole. Acanthamoeba cutis poses unique diagnostic challenges in a setting of novel agents for chronic lymphocytic leukemia and may be underrecognized. With the expanding population of immunocompromised patients, rare cutaneous infections should enter the differential early on along with early consideration of molecular ancillary testing. The long-term immunomodulating properties of acalabrutinib remain to be elucidated.

Abstract: In this unusual case, a 73-year-old woman presented with bloody discharge from her right breast and skin thickening was observed on subsequent imaging. Clinically, the findings raised concern for Paget disease. A skin punch biopsy was performed, revealing a high-grade infiltrating carcinoma with squamous features. Metaplastic carcinoma was a differential diagnosis, given that this patient had a history of invasive ductal carcinoma and radiation treatment in the same breast. A subsequent central lumpectomy confirmed the diagnosis of invasive squamous cell carcinoma of the nipple, occurring in the context of Bowen disease as a precursor lesion. Notably, there was no evidence of ductal carcinoma in situ in the background breast tissue or conventional invasive ductal carcinoma component. Both in situ and invasive forms of squamous cell carcinomas have been rarely reported in the nipple. This case highlights the importance of considering such a rare diagnosis, especially in patients with a history of breast cancer.

Abstract: Several cutaneous neurovascular stromal lesions are clinically and pathologically ill-defined entities. They are known by different nomenclatures, often unrecognized, misinterpreted, and confused with other skin lesions. Reports have documented cases of palmar and oral lesions in both children and adults. There is uncertainty regarding their true prevalence, clinicopathologic characteristics, and classification. Our aim is to highlight the salient histopathologic, histochemical, and immunohistochemical features of acral nodular tumors showing perineuriomatous differentiation. We found 3 teenagers (0.2%) [2 females, 1 male, average age: 13 years] with hand nodules out of 1331 patients with cutaneous and oral polypoid lesions. They were isolated, asymptomatic, nontraumatic, subcentimetric, palmar, digital nodules with an average duration of 5 years. They demonstrated dermal-based anomalous growths composed of thick tortuous neurovascular bundles and collagenous fibrovascular stroma. Masson trichome demarcated micronodular and plexiform neurovascular bundles showing concentric onion-bulb whorls ensheathed in collagenous fibrovascular stroma. Elastic fibers were absent. Alcian blue demonstrated intraneural mucinous alteration and loose interstitial myxoid mesenchyme. CD31, ERG, and smooth muscle actin highlighted small intraneural capillary-sized, and larger venous and arteriolar interstitial vasculatures. CD34 decorated the interstitial mesenchyme. S100, SOX10, and neurofilament revealed sparse neural components, whereas EMA and GLUT1 highlighted prominent perineurial components within the neurovascular bundles and onion-bulb micronodules. The findings suggest that cutaneous intraneural pseudoperineurioma nodules may represent a distinct clinicopathologic entity among traumatic neuromas, resembling cutaneous intraneural perineurioma. Further validation studies are necessary because of the small size of the case series and the lack of molecular genetic studies.

Abstract: Cutaneous myxomas are extremely rare in the pediatric population. We describe a case of an eyelid cutaneous myxoma with multiple recurrences in an 8-year-old child. The lesion once previously diagnosed as eccrine hidrocystoma had been excised three times with subsequent recurrence. Frozen section diagnosis performed during the fourth excision showed striking basaloid features, prompting deferral of definitive diagnosis to permanent sections. Following routine processing, basaloid proliferations were again seen without significant atypia or mitotic activity in addition to background features of myxoma. CD10 immunostain highlighted both basaloid nests and surrounding stroma. Cutaneous myxoma was diagnosed. The diagnosis was corroborated by an external consultation. The patient underwent genetic testing for the Carney complex with negative results. This case report raises some practical points. First, due to their rarity in the pediatric population and potential to mimic other entities, cutaneous myxomas can be misdiagnosed as other benign neoplasms. Second, although induction of basaloid proliferation has been well-documented in myxoma, it can be easily misinterpreted as a malignant process, particularly in the setting of a frozen section diagnosis and lack of available clinical information. Third, even though solitary cutaneous myxomas are less likely to be associated with the Carney complex, a possibility of such an association should always be born in mind, as consequences of missing syndromic neoplasms, such as cardiac myxoma, can be lethal.

Abstract: Peripheral nerve sheath tumors can include neurofibroma, schwannoma, and perineurioma, with hybrid nerve sheath tumor (HNST) being rare. We describe 3 HNST cases with epithelioid schwannoma and neurofibroma features, an uncommon manifestation of hybrid schwannoma/neurofibroma. The 3 cases involved the upper back, forearm, and thigh. Histopathologically, the tumors were located in the subcutis or dermis and subcutis. The epithelioid schwannoma component showed nests/cords of epithelioid cells with round nuclei and abundant cytoplasm. In contrast, the neurofibroma component showed spindle cell proliferation within myxoid stroma. The 3 cases showed variable proportions of both components. Immunohistochemically, the epithelioid schwannoma components were positive for S100 protein and negative for CD34, whereas the neurofibroma component showed partial S100 immunoreactivity and contained abundant CD34-positive cells with a fingerprint pattern. Epithelial membrane antigen and GLUT1 revealed the perineurial capsules. In conclusion, our cases expand the morphologic spectrum of HNST and underscore the importance of recognizing this variant.

Abstract: Cutaneous vasculitis, either as a single organ or part of systemic vasculitis, can take various forms. Granulomatosis with polyangiitis (GPA) is characterized by necrotizing granulomatous inflammation in the respiratory tract and vasculitis affecting small- to medium-sized blood vessels. Skin-limited GPA, an uncommon presentation, poses diagnostic challenges and may result in delayed diagnosis. We describe a 32-year-old man with painful ulcers and black eschars on both lower limbs, evolving from purpura. Despite lacking typical anti neutrophil cytoplasmic antibodies and systemic involvement, histopathology revealed granulomatous vasculitis. Treatment with prednisolone and methotrexate led to complete symptom resolution within 8 months. Skin-limited GPA, often without anti neutrophil cytoplasmic antibody positivity, warrants clinical suspicion, early intervention, and increased awareness to enhance patient outcomes.