American Journal of Dermatopathology最新文献

Background: Focal acantholytic dyskeratosis (FAD) and epidermolytic hyperkeratosis (EHK) are common incidental epidermal histologic findings within dysplastic nevi biopsies. We evaluate whether areas of FAD and EHK within dysplastic nevi biopsies stain with immunostains used to characterize melanocytic neoplasms.

Methods: In this case series, a natural language search of histopathology reports from our institution in the past year (2020-2021) identified dysplastic nevus biopsies with concurrent FAD and/or EHK. Tissue samples were examined for positive melanocytic immunostaining with SOX-10 and Melan-A in areas of FAD and EHK.

Results: Out of 32 biopsies, 20 of 26 FAD specimens (76.9%) and 2 of 6 EHK specimens (33.3%) showed unexpected suprabasal layer staining with a melanocytic marker that did not correspond to definitively identified melanocytes on the H&E-stained sections. The immunohistochemical staining of FAD and EHK was observed in 2 forms: nonspecific background staining or "true" staining (ie, seemed nuclear on SOX-10 or cytoplasmic on Melan-A).

Conclusions: This pilot examination provides evidence that areas of incidental FAD within dysplastic nevi biopsies demonstrate unexpected suprabasal layer staining with melanocytic markers. When dermatopathologists evaluate melanocytic neoplasms with melanocytic markers, it is possible the presence of incidental FAD could lead to over diagnosing pagetoid scatter within these lesions. This study is a proof of concept with mild to moderately dysplastic nevi that do not typically incur the use of melanocytic stains; however, the implication of this unexpected staining pattern would be important when using melanocytic markers on borderline melanocytic neoplasms that have incidental FAD. Close correlation with H&E is imperative to prevent misinterpretation in these cases.

Abstract: Microsecretory adenocarcinoma (MSA) was first described in 2019 as a low-grade salivary gland neoplasm of intraoral origin with distinct histopathologic features and a characteristic  MEF2C::SS18  fusion. Recently, skin was also identified as a primary site for MSA in a report by Bishop et al. Due to its rarity and resemblance to other adnexal tumors, MSA is a challenging diagnosis. Herein, we present a case of cutaneous MSA that was unique for the presence of a significant microcystic component and marked adnexal hyperplasia, which mimicked myxoid microcystic adnexal carcinoma (MAC). A 58-year-old presented with a 1 year history of an enlarging eyelid nodule. Histopathologic analysis revealed dermal tumor composed of small tubules containing inspissated bluish mucinous material. Accompanying marked adnexal hyperplasia and many microcysts were also present. Tumor cells expressed S100 protein, which is distinct from MAC, while p63 immunohistochemistry showed marked loss of myoepithelial labeling, as is common in primary adenocarcinomas. Next generation gene sequencing detected the characteristic MSA fusion protein  MEF2c::SS18 . We report a novel presentation of MSA that simulated MAC because of the presence of associated microcystic change. The presence of S100 immunopositivity and the identification of  MEF2C::SS18  fusion confirmed the diagnosis of cutaneous MSA.

Abstract: Pulse granulomas are unusual foreign body reactions to exogenous plant material, featuring the presence of hyaline ring structures and granulomatous inflammation. Pulse granulomas have been reported to occur in the oral cavity, gastrointestinal tract, and respiratory tract. Cutaneous pulse granulomas are exceedingly rare. All reported cases have been closely associated with underlying pathology such as chronic inflammatory conditions, trauma, or surgical procedures which likely facilitated implantation of exogenous plant material. We report a novel case of a cutaneous pulse granuloma presenting in the perianal region of an otherwise healthy man. The authors propose that the source of the exogenous plant material is plant-derived baby wipes, which the patient had been using daily to the perianal region.

Abstract: Malignant proliferating pilar tumors (MPPTs) are rare, unique cutaneous adnexal tumors. Sarcomatous transformation in MPPTs is even rarer (4 previous cases reported). Here, we report an extraordinary case of a MPPT with sarcomatous transformation occurring on the scalp of a 63-year-old man with an in-depth molecular profile along with histologic, immunohistochemical, and follow-up data. Shared mutations in the epithelial and sarcomatous components included a loss-of-function TP53 mutation. An inactivating TP53 mutation was only identified in the epithelial component, and an inactivating CDKN2A mutation was only identified in the sarcomatous component. Copy number variations previously reported in MPPT were also identified, including 6p21.1 loss, 6q arm loss, and 15q21.1-q26.3 gain [epithelial], and 6p22.2-p22.3 loss [sarcoma]. Histologically, the tumor demonstrated juxtaposed areas of proliferating pilar tumor, carcinoma with clear cell change, and sarcomatous areas that did not stain for AE1/AE3, p40, CD34, S100 protein, and smooth muscle actin  by immunohistochemistry. The patient is alive at 2 years without evidence of recurrence or metastasis.

Abstract: Pyoderma gangrenosum (PG) is a rare inflammatory neutrophilic dermatosis that is difficult to diagnose due to non-specific clinical, laboratory, and histopathologic features. Distinguishing pseudoepitheliomatous hyperplasia (PEH) from squamous cell carcinoma (SCC) is also histopathologically challenging. The connection between PEH and PG is not well recognized, and instances of PG mimicking SCC are rare. We report a case of vegetative PG accompanied by PEH, originally mistaken for SCC. A 78-year-old woman presented with a 3-month history of an ulcerated, exophytic, and painful mass on her right lower leg. An incisional biopsy revealed PEH and neutrophilic microabscesses, initially raising concerns for SCC keratoacanthoma type with PEH or well-differentiated, infiltrative SCC. However, following additional review of clinical and histopathologic findings at the cutaneous oncology tumor board, the diagnosis of vegetative PG with associated PEH was favored. This case highlights the significance of recognizing PEH as a histopathology feature that can be seen in PG and lead to difficulty distinguishing PG with PEH from SCC. We stress the importance of promptly diagnosing PG through clinical and histopathologic correlation to prevent diagnostic delays and unnecessary surgeries or treatments.

Abstract: Superficial CD34+ fibroblastic tumor (SCD34FT) is a relatively recently described borderline mesenchymal neoplasm. Owing to a relative lack of specificity in clinical presentation, radiopathologic findings, and immunohistochemical staining, the diagnoses of SCD34FT can be challenging. In this study, we present a case of a 55-year-old woman with an indolent painless nodule on the right shin. Histopathologic evaluation of the resected specimen showed a moderately cellular, subcutaneous lesion composed of spindled cells with mild pleomorphism arranged in sheets and fascicles. Immunohistochemical staining demonstrated diffuse positivity for CD34. Surprisingly, the tumor also showed diffuse expression of smooth muscle actin (SMA) and more than focal (ranging from subset to diffuse) expression of AE1/AE3 and CAM5.2. DNA and RNA next-generation sequencing revealed a t(X; 11)(q13; q24) MED12::PRDM10 fusion, confirming the diagnosis of SCD34FT. To the best of our knowledge, this is the first reported case highlighting SCD34FT with more extensive immunoreactivity to epithelial markers (AE1/AE3 and CAM5.2) and SMA compared with the focal staining reported in the existing literature. We hope that adding this case to the existing literature will raise awareness among pathologists to recognize the more variable staining pattern of epithelial markers and SMA when considering the diagnosis of SCD34FT.

Abstract: Primary cutaneous anaplastic large cell lymphoma (pcALCL) is a CD30+ lymphoproliferative disorder with generally favorable outcomes and infrequent extracutaneous spread, usually limited to local lymph nodes. However, there may be extensive histologic overlap with more aggressive CD30+ lymphomas, such as large cell transformation of mycosis fungoides or secondary skin involvement by anaplastic lymphoma kinase (ALK)-negative anaplastic large cell lymphoma. Definitive diagnosis relies on clinicopathologic correlation. We report on a 26-year-old woman who presented to our institution with progressive lower extremity wounds for several months, previously treated with antibiotics and vacuum-assisted closure dressings. Consultation with dermatology and 2 separate biopsies eventually led to the diagnosis of pcALCL. Subsequent imaging revealed stage IV disease with innumerable intensely fluorodeoxyglucose (FDG)-avid subcutaneous, intramuscular, and visceral foci, but paucity of lymph node involvement. The patient's condition deteriorated, and she died during her hospitalization. This case reviews the clinicopathologic findings of pcALCL, emphasizes the importance of clinicopathologic correlation in differentiating between CD30+ lymphoproliferative disorders, highlights the extremely rare phenomenon of systemic intramuscular and visceral disseminated disease occurring in pcALCL, and discusses implications for prognosis.