Dermatopathology最新文献

Cutaneous squamomelanocytic tumor (SMT) is a very rare cutaneous malignancy, composed of a dual phenotypic population of both malignant melanocytes and keratinocytes, intimately intermingled together. Herein, we report a new case of a SMT occurring in an 82-year-old man, located on the scalp. Histopathology revealed a mixed population consisting of squamous cell carcinoma and melanoma within the same lesion, also confirmed using immunohistochemical staining for high molecular-weight cytokeratins (HMWCKs) and Melan-A. Moreover, to the best of our knowledge, for the first time, we tested SMT for the preferentially expressed antigen in melanoma (PRAME), which revealed a strong and diffuse positivity in the melanocytic component. These tumors need to be distinguished by more frequent collision tumors and colonization. Furthermore, we provide a comprehensive review of the literature, focusing on clinical and histopathological aspects, biological behavior and still-debated, but fascinating histogenesis of this elusive entity.

The diagnostic utility of immunohistochemistry on paraffin-embedded sections in bullous disorders is useful when frozen tissue is not available. In pemphigus vulgaris and pemphigus foliaceus, an intercellular lace-like staining pattern of IgG4 on lesional tissue by immunohistochemistry has been described, with a comparable sensitivity and specificity to direct immunofluorescence on perilesional tissue. This study aimed to evaluate the staining pattern of IgG4 in non-immunobullous disorders to highlight the potential pitfalls when using this stain. In this study, we conducted a retrospective review of our institution's database of non-immunobullous disorders where immunohistochemistry of IgG4 was performed to rule out pemphigus. We identified 27 cases where IgG4 immunohistochemistry was performed and observed intercellular IgG4 staining in some cases of Grover disease, bullous impetigo, irritated dermal hypersensitivity reaction, acantholytic actinic keratosis, and graft versus host disease. Our results indicate that the interpretation of IgG4 staining by immunohistochemistry in cutaneous acantholytic disorders should be approached with caution. Confirmation on cryosections with direct immunofluorescence study results is important in these settings.

Paediatric dermatology is still an expanding subspeciality, which is well illustrated by the growing number of books and articles that have been published on this subject in recent years [...].

PRAME (PReferentially expressed Antigen in MElanoma) is a tumor-associated antigen first identified in tumor-reactive T-cell clones derived from a patient with metastatic melanoma. Immunohistochemistry (IHC) for PRAME is useful for diagnostic purposes to support a suspected diagnosis of melanoma. Anecdotally, PRAME has been observed to stain sebaceous units in glands in background skin. We examined the expression of PRAME in adnexal lesions and common skin cancers to determine whether it is of potential diagnostic utility in supporting the differentiation between sebaceous and non-sebaceous lesions. IRB approval from Mount Sinai Medical Center (MSMC) was obtained. This is a single-center retrospective cohort analysis over a ten-year period (1 January 2012, and 31 December 2023). We used the pathological database of skin lesions, including sebaceous, sweat gland, and follicular lesions, in addition to basal cell carcinomas (BCCs) and squamous cell carcinomas (SCCs), from 81 patients who underwent shave/punch biopsies or surgical excisions. We evaluated the IHC staining percentage positivity and intensity for PRAME. Staining intensity was subcategorized into negative, weak, moderate, and strong, whereas expression percentage positivity was subcategorized into 0%, 1-25%, 26-50%, 51-75%, and 76-100%. Most sebaceous versus non-sebaceous lesions exhibited cytoplasmic staining of moderate to strong intensity in >75% of cells. PRAME has a sensitivity and specificity of 100.0% and 86.7%, respectively, to support distinguishing between sebaceous and non-sebaceous adnexal lesions (regardless of whether they are benign or malignant). BCCs and SCCs showed weak to moderate nuclear staining for PRAME in >75% of cells. None of the 13 lesions of hair follicle origin showed any staining. A total of 26 of the 32 lesions of sweat gland origin were negative while 6 (18.75%) showed positive staining. In conclusion, we confirm the potential utility of PRAME for supporting the distinction between sebaceous and non-sebaceous adnexal lesions on one hand, and on the other, distinguishing BCC and SCC that may show nuclear staining from sebaceous carcinoma that shows cytoplasmic staining.

Malignant proliferating trichilemmal tumors (MPTTs), arising from the external root sheath of hair follicles, are exceptionally rare, with limited documentation of their genetic alterations. We present a case of a 64-year-old African American woman who initially presented with a gradually enlarging nodule on her posterior scalp. An initial biopsy at an outside hospital suggested metastatic adenocarcinoma or squamous cell carcinoma (SCC) of an uncertain origin. A subsequent wide local excision revealed a 2.0 cm tumor demonstrating characteristic trichilemmal keratinization, characterized by an abrupt transition from the nucleated epithelium to a laminated keratinized layer, confirming MPTT. Immunohistochemistry demonstrated diffuse p53 expression, patchy CD 34 expression, focal HER2 membranous expression, and patchy p16 staining (negative HPV ISH). A molecular analysis identified TP53 mutation and amplifications in the ERBB2 (HER2), BRD4, and TYMS. Additional gene mutations of uncertain significance included HSPH1, ATM, PDCD1 (PD-1), BARD1, MSH3, LRP1B, KMT2C (MLL3), GNA11, and RUNX1. Assessments for the homologous recombination deficiency, PD-L1 expression, gene rearrangement, altered splicing, and DNA mismatch repair gene expression were negative. The confirmation of ERBB2 (HER2) amplification in the MPTT through a molecular analysis suggests potential therapeutic avenues involving anti-HER2 monoclonal antibodies. The presence of the TP53 mutation, without the concurrent gene mutations typically observed in SCC, significantly aided in this differential diagnosis.

Digital papillary adenocarcinoma (DPAC) is a rare, low-grade sweat gland carcinoma primarily found on the hands, fingers, or toes and predominantly affecting males. Distinguishing DPAC from benign sweat gland tumors can be challenging. We present the case of a 52-year-old patient with a progressive tumor on the finger initially misdiagnosed as a viral wart. Histological examination revealed a cytologically basophilic sweat gland tumor with tubular structures, papillary protrusions, and a characteristic immunohistochemical staining pattern for CK 7 and Actin. HPV-42 positivity and molecular analysis confirmed the diagnosis of DPAC. HPV-42 has been strongly associated with DPAC. Additionally, p16 positivity and BRAFV600E negativity were observed. These findings aid in the differential diagnosis of acral sweat gland tumors and guide clinical management, including with respect to the potential for recurrence and metastasis.

Spindle cell lipoma (SCL) is a benign adipocytic tumor usually found in the subcutis of the posterior neck, upper back, and shoulder, predominantly in middle-aged males. This case report describes an atypical presentation of SCL in a 26-year-old male with a history of malignant melanoma. The patient presented with an erythematous plaque with central hyperpigmentation on the right upper arm, an uncommon location and presentation for SCL. Histopathological examination revealed an atypical myxoid spindle cell neoplasm with CD34 positivity and an overlying mildly atypical compound melanocytic nevus. The unusual clinical and histological features, combined with the patient's melanoma history, complicated the differential diagnosis, which included dermatofibrosarcoma protuberans (DFSP) and solitary fibrous tumors (SFTs). A wide local excision with 2 cm margins was performed, and subsequent pathology confirmed clear margins, supporting the diagnosis of SCL. This case highlights the importance of including SCL in the differential diagnosis of CD34-positive spindle cell tumors, even when clinical and histological presentations are atypical, and underscores the need for thorough histopathological evaluation and a broad differential diagnosis in patients with a history of melanoma.

The dermoscopic rainbow pattern (RP), also known as polychromatic pattern, is characterized by a multicolored appearance, resulting from the dispersion of polarized light as it penetrates various tissue components. Its separation into different wavelengths occurs according to the physics principles of scattering, absorption, and interference of light, creating the optical effect of RP. Even though the RP is regarded as a highly specific dermoscopic indicator of Kaposi's sarcoma, in the medical literature, it has also been documented as an atypical dermoscopic finding of other non-Kaposi skin entities. We aim to present two distinct cases-a pigmented basal cell carcinoma (pBCC) and an aneurysmatic dermatofibroma-that exhibited RP in dermoscopy and to conduct a thorough review of skin conditions that display RP, revealing any predisposing factors that could increase the likelihood of its occurrence in certain lesions. We identified 33 case reports and large-scale studies with diverse entities characterized by the presence of RP, including skin cancers (Merkel cell carcinoma, BCC, melanoma, etc.), adnexal tumors, special types of nevi (blue, deep penetrating), vascular lesions (acroangiodermatitis, strawberry angioma, angiokeratoma, aneurismatic dermatofibromas, etc.), granulation tissue, hypertrophic scars and fibrous lesions, skin infections (sporotrichosis and cutaneous leishmaniasis), and inflammatory dermatoses (lichen simplex and stasis dermatitis). According to our results, the majority of the lesions exhibiting the RP were located on the extremities. Identified precipitating factors included the nodular shape, lesion composition and vascularization, skin pigmentation, and lesions' depth and thickness. These parameters lead to increased scattering and interference of light, producing a spectrum of colors that resemble a rainbow.

Akatsuki disease (also known as pomade crust) is characterized by skin lesions resulting from inadequate skin hygiene. It is sometimes influenced by underlying psychological factors. Akatsuki disease sometimes mimics cutaneous horn or skin cancer. However, there are no previous reports of skin cancer accompanied with Akatsuki disease. Herein, we report a 79-year-old woman who was referred to our department with a tumor on her left cheek. Before performing a biopsy, we recommended that her family assist with regular facial cleansing. Two months later, the scales and crusts on her entire face had disappeared and the tumor on the left cheek had reduced. Skin biopsy was performed, and histological examination revealed ulcerative basaloid lobules consisting of cells with a small cytoplasm and large hyperchromatic nuclei. Peripheral palisading and tumor-stroma clefting were observed. A diagnosis of basal cell carcinoma was made.

Non-melanoma skin cancers (NMSCs), including basal cell carcinoma (BCC) and squamous cell carcinoma (SCC), are highly prevalent and a significant cause of morbidity. Image-guided superficial radiation therapy (IGSRT) uses integrated high-resolution dermal ultrasound to improve lesion visualization, but it is unknown whether efficacy varies by histology. This large retrospective cohort study was conducted to determine the effect of tumor histology on freedom from recurrence in 20,069 biopsy-proven NMSC lesions treated with IGSRT, including 9928 BCCs (49.5%), 5294 SCCs (26.4%), 4648 SCCIS cases (23.2%), and 199 lesions with ≥2 NMSCs (1.0%). Freedom from recurrence at 2, 4, and 6 years was 99.60%, 99.45%, and 99.45% in BCC; 99.58%, 99.49%, and 99.49% in SCC; and 99.96%, 99.80%, and 99.80% in SCCIS. Freedom from recurrence at 2, 4, and 6 years following IGSRT did not differ significantly comparing BCC vs. non-BCC or SCC vs. non-SCC but were slightly lower among SCCIS vs. non-SCCIS (p = 0.002). There were no significant differences in freedom from recurrence when stratifying lesions by histologic subtype. This study demonstrates that there is no significant effect of histology on freedom from recurrence in IGSRT-treated NMSC except in SCCIS. These findings support IGSRT as a first-line therapeutic option for NMSC regardless of histology.