Search Results (18)

Background/Objectives: Trichoblastoma is a benign follicular adnexal tumor that typically arises on the head and neck. Large variants at atypical locations pose considerable diagnostic challenges because their clinical presentation can be indistinguishable from malignant soft tissue neoplasms. Herein, we describe a case of trichoblastoma presenting as a large subcutaneous thigh mass that was correctly diagnosed by fine-needle aspiration cytology. Case Presentation: A 49-year-old male presented with a 7 cm, slowly enlarging, subcutaneous mass in the left thigh of 20 years’ duration. Magnetic resonance imaging raised the possibility of a low-grade sarcoma. Fine-needle aspiration cytology yielded cohesive clusters of basaloid cells with peripheral palisading, delicate spindle-shaped follicular stromal cells intimately admixed with the epithelial component, and orangeophilic keratinous material in the background. The absence of nuclear atypia, mitotic figures, and mucinous stroma supported a preoperative cytological diagnosis of a benign follicular germinative tumor consistent with trichoblastoma, thereby guiding conservative surgical excision. Histopathological examination confirmed the diagnosis. Immunohistochemistry revealed focally positive BerEP4, CD34-positive stroma, negative androgen receptor, and positive bcl-2, consistent with trichoblastoma and distinguishing the tumor from basal cell carcinoma. The patient remained recurrence-free 12 months after surgery. Conclusions: Careful assessment of characteristic cytomorphological features, particularly a dual population of basaloid epithelial cells with peripheral palisading and specialized follicular stromal cells, is vital for the accurate preoperative cytological characterization of trichoblastoma, even at atypical anatomical sites. Full article

Background/Objectives: Aggressive variants of prostate cancer pose significant diagnostic and prognostic challenges due to atypical imaging appearances, variable prostate-specific antigen behavior, and distinct molecular features. Conventional imaging may underestimate their biological aggressiveness. This review aimed to synthesize current evidence on imaging characteristics, biomarker dynamics, tumor localization, histology, and radiomic features of aggressive prostate cancer variants, and to evaluate the potential role of radiomics in early recognition and risk stratification. Methods: A structured narrative review was performed of studies reporting imaging, clinical, and molecular features of aggressive prostate cancer variants. Imaging modalities included multiparametric magnetic resonance imaging, positron emission tomography with prostate-specific membrane antigen or fluorodeoxyglucose, bone scintigraphy, and transrectal ultrasound. Data on prostate-specific antigen levels and kinetics, intraprostatic tumor location, tumor size, metastatic patterns, and molecular alterations were extracted. Evidence for rare entities such as basaloid and primary squamous carcinomas was derived from published case reports and series, while selected variants were complemented by institutional imaging and histopathologic observations. Results: Neuroendocrine and small cell carcinomas frequently showed low prostate-specific antigen levels, high fluorodeoxyglucose uptake, low prostate-specific membrane antigen expression, and central or transitional zone involvement with large tumor size at diagnosis. Ductal adenocarcinoma demonstrated marked diffusion restriction and elevated prostate-specific antigen, whereas basal cell carcinoma often appeared inconspicuous on conventional imaging. Radiomic analysis consistently captured tumor heterogeneity and spatial complexity beyond standard qualitative metrics. Conclusions: Aggressive prostate cancer variants represent a diagnostic blind spot in routine imaging. Radiomics offers complementary quantitative information that may improve early detection, subtype differentiation, and risk stratification when integrated into multimodal imaging workflows. Further prospective and radiogenomic studies are warranted to validate these findings. Full article

Targetable gene alterations have become increasingly important in the treatment of cancers. Thirty STK11-mutated lung cancers from 199 cases with molecular profiling performed during 2016–2024 were studied for clinical, morphologic, immunohistochemical (IHC) and molecular features. Of the 30 STK11-mutated lung cancers, 29 were lung adenocarcinomas (LADCs) and 1 was large cell neuroendocrine carcinoma (LCNEC). STK11 mutation was not found in other subtypes of lung cancers. Of the 29 STK11-mutated LADCs, 6 (21%) were mucinous and 23 (79%) were non-mucinous. Of the 19 non-mucinous LADCs with sufficient material for IHC, 9 (47%) displayed acinar/papillary/lepidic patterns, 8 (42%) were poorly differentiated (solid/trabecular/basaloid/complex glandular), and 2 (11%) had mixed solid and acinar patterns. The most common concurrent altered genes were KRAS (52%), followed by TP53 (38%), KEAP1 (34%), and DNA repair genes (BRCA2/ATM) (21%). A total of 6/15 (40%) LADCs with a KRAS mutation presented with mucinous morphology. Concurrent EGFR, ROS, or ALK alterations with STK11 mutation were rare or non-existent. Of the 3 LADCs with SMARCA4 deficiency, 2 were mucinous and 1 had basaloid/adenoid cystic-like features. All the cases were microsatellite stable (MSS). The majority (55%) had low TMB (<10). Most (86%) had PD-L1 TPS 0 or <5%. Among the 14 non-mucinous LADCs with IHC performed, 5 (36%) were TTF-1-negative and all displayed poorly differentiated morphology. Overall, 8/10 (80%) of poorly differentiated components in non-mucinous LADCs were negative for TTF-1. In contrast, all LADCs with better differentiated patterns (acini/papillary/lepidic) were positive for TTF-1. The majority (14/21, 67%) of patients with available follow-up presented with metastasis. Full article

Dermatofibromas (DFs) are benign neoplasms of the dermis typically found on the extremities of young adults. In approximately 3–5% of cases, basaloid cell hyperplasia (BCH) is observed overlying DFs. BCH is characterized by the proliferation of basaloid cells within the epidermis. BCH and superficial basal cell carcinoma (BCC) share many histological features, making their differentiation challenging. It is therefore unclear if the proliferation of basaloid cells in DFs represents an inductive process or, conversely, a malignant transformation indicative of BCC. The primary objective of our study was to determine whether BCH can be distinguished from superficial BCC using histology and immunhistological techniques. The histological and immunohistochemical characteristics of 43 DF samples with overlying BCH revealed significant similarities in staining patterns with those of superficial BCC described in the literature. These findings point to the need for innovative methods, such as molecular techniques, to refine diagnostic accuracy. Full article

Background/Objectives: Squamous cell carcinoma of the nail unit (SCCNU) is a rare yet often underrecognized malignancy that can lead to delayed diagnosis and significant functional morbidity. This review aims to comprehensively summarize the current understanding of SCCNU, focusing on its clinical, dermoscopic, and molecular features, diagnostic approaches, and evolving management strategies, including the role of emerging technologies and immunotherapy. Methods: A detailed literature review was conducted using peer-reviewed publications, case series, and institutional guidelines related to SCCNU. Emphasis was placed on studies addressing clinical presentation, dermoscopic patterns, molecular pathology, histologic subtypes, imaging, biopsy techniques, staging systems, and both conventional and novel therapeutic approaches. Comparative analyses of histopathological variants and diagnostic algorithms were included. Results: SCCNU presents in patients with diverse clinical manifestations, often mimicking benign nail disorders, leading to diagnostic delays. Dermoscopy improves lesion visualization, revealing features such as vascular changes and onycholysis. Histologically, SCCNU exhibits two main subtypes: basaloid (HPV-related) and keratinizing (HPV-negative) types. Molecular analyses have identified TP53 as the most frequently mutated gene, with additional alterations in HRAS, BRAF, and TERT. Imaging modalities such as MRI and LC-OCT aid in staging and surgical planning. Management is centered on complete excision—often via Mohs micrographic surgery—while topical, intralesional, and HPV-directed therapies are under investigation. Immunohistochemical markers (p16, Ki-67, AE1/AE3) and neoadjuvant immunotherapy represent promising adjuncts. Conclusions: Early diagnosis through non-invasive imaging, improved molecular characterization, and personalized treatment strategies are essential to advancing care in SCCNU. Future directions include clinical trials evaluating immunotherapy, vaccine strategies, and precision-guided surgical approaches to preserve function and minimize recurrence. Full article

Penile intraepithelial neoplasia (PeIN) is a rare but clinically significant condition that can progress to invasive squamous carcinoma. Early diagnosis is crucial but often challenging due to its heterogeneous clinical and dermoscopic presentation, which can mimic other benign or malignant lesions. In this study, we report two cases of pigmented penile lesions evaluated using non-invasive imaging techniques: reflectance confocal microscopy (RCM) and line-field confocal optical coherence tomography (LC-OCT). Both methods revealed characteristic features such as hyperkeratosis, parakeratosis, acanthosis, nuclear pleomorphism of keratinocytes, and the presence of bright intraepithelial dendritic cells, correlating closely with histopathological findings of high-grade basaloid PeIN. Our findings highlight the valuable role of RCM and LC-OCT in improving the differential diagnosis of genital lesions, potentially reducing the need for invasive diagnostic procedures and ensuring early, appropriate management. Full article

Dermatofibromas (DFs) represent prevalent benign fibrohistiocytic tumors, typically manifesting as solitary lesions. In the majority of cases, the clinical presentation and dermoscopic and histopathological features of DFs adhere to a characteristic profile. However, DFs may exhibit atypical clinical presentations and, more commonly, histologic attributes, posing challenges in differential diagnosis. Both DFs and basal cell carcinomas (BCCs) are frequently encountered cutaneous lesions, each characterized by distinct clinical and dermoscopic features and microscopic morphology. The simultaneous occurrence of these two entities within the same lesion is rare. DFs have been documented to form collision tumors in conjunction with a spectrum of benign and malignant lesions, encompassing not only BCC but also balloon cell nevus, squamous cell carcinoma (SCC), and melanoma. Alterations in the epidermis overlaying a DF range from simple hyperplasia to the proliferation of basaloid cells. Accurate diagnosis, leading to the complete excision of the lesion, is contingent upon the recognition of dermoscopic criteria, precluding misinterpretation as a benign lesion. We present two cases of collision tumors comprising DF and BCC. This case report underscores the paramount importance of dermoscopy and adherence to dermoscopic criteria in the assessment of collision lesions and the diagnostic process related to cutaneous malignancies. Full article

In canine mammary neoplasms, greater inflammation is associated with higher histological grade, lymphatic invasion, and metastases. This retrospective study assessed the density of peri- and intratumoral tumor-infiltrating lymphocytes (TILs), tumor-associated neutrophils (TANs), and CD3⁺ and CD79⁺ lymphocytes in canine mammary neoplasms with a solid arrangement, and associated such data with histological types, immunophenotype, prognostic factors, cyclooxygenase-2 (Cox-2) expression and overall and cancer-specific survival. Sixty-one neoplasms with a solid arrangement were classified as malignant myoepitheliomas (6/9.8%), solid papillary carcinomas (8/13.1%), carcinomas with a solid pattern (9/14.8%), basaloid carcinomas (BC) (19/31.1%), and malignant adenomyoepitheliomas (19/31.1%). Intra- and peritumoral TILs, TANs, and TCD3⁺ and BCD79⁺ lymphocytes were counted, and based on the resulting median, the neoplasms were divided into low or high cell infiltration. BCs had the lowest density of intratumoral TILs (p = 0.02), and luminal B neoplasms showed a significantly higher density of intratumoral TCD3⁺ than luminal A cases. Neoplasms with a higher density of peritumoral CD3⁺ and CD79⁺ had significantly greater proliferative activity. High infiltration of intratumoral BCD79⁺ lymphocytes was related to nodal metastasis (p = 0.03). Intratumoral TILs and TCD3⁺ were associated with shorter survival time. Therefore, intratumoral lymphocyte infiltration is possibly an important feature in the progression of cancer and influences the survival in bitches with solid arrangement neoplasms. Full article

A seven-year-old spayed female dog presented with multiple, small oval-shaped masses on the abdominal skin. The excised tissue was submitted for histopathological evaluation. Routine histology revealed basaloid nodules with stippled chromatin and pleomorphic nuclei. Morphologically, the tumor resembled a solid papillary carcinoma of the breast or an endocrine mucin-producing sweat gland carcinoma (EMPSGC). EMPSGC is a rare neuroendocrine-differentiated neoplasm. This study aimed to compare different immunohistochemical markers for distinguishing between canine sweat gland carcinoma (SGC) and mammary gland carcinoma (MGC). CK19 and Sox9 were useful in identifying SGC. Additionally, the tumor was positive for CK5, AE1/AE3+CK8/18, p63, vimentin, E-cadherin, and synaptophysin, while estrogen receptor staining was negative. The final diagnosis of canine EMPSGC was based on the tumor’s morphological and neuroendocrine immunohistopathological features. Our report provides the first detailed description of a canine EMPSGC, an exceedingly rare tumor in dogs. Full article

A 74-year-old woman in good general health presented with a 5-year history of progressive hair loss over several years, interpreted as female androgenetic alopecia (AGA), and was treated with topical 5% Minoxidil without improvement. The patient’s relevant medical history revealed infiltrating, triple-negative apocrine carcinoma of the right breast four years before, treated by quadrantectomy, radiation, lymphadenectomy and chemotherapy, with no recurrence at the last follow-up. On examination, there was an asymptomatic 15 × 15 cm firm and whitish area of scarring alopecia on the central scalp. Dermoscopy revealed multiple arborizing vessels and many telangiectasia. The clinical considerations included mainly cutaneous metastasis of breast carcinoma (alopecia neoplastica), pseudopelade of Broque and morpheaform basal cell carcinoma (BCC). A histopathologic examination revealed characteristic changes of morpheaform BCC with basaloid islands and cords of atypical basaloid cells diffusely infiltrating the dermis, embedded in a sclerotic and hypervascularized stroma. Secondary alopecia neoplastica due to morpheaform BCC on the scalp is an exceedingly rare entity, possessing subtle clinical features that may mimic both scarring and non-scarring alopecia. Delayed recognition may contribute to aggressive behavior and extensive local destruction. Treatment with hedgehog inhibitors in locally advanced BCC of the scalp, both in adjuvant and neoadjuvant modalities, is promising. Full article

Adenoid cystic carcinoma (AdCC) is known to behave differently based on its location, histologic features, and molecular profile. Despite this understanding, efforts to use these molecular findings to develop personalized treatments have not yet been successful. The purpose of this retrospective study is to examine the molecular characteristics of AdCC with various histologic features in three different locations. A reference group of 20 classic cribriform AdCC cases from the parotid gland was included, along with 10 salivary AdCCs (Group 1), 10 sinonasal AdCCs with hyalinization (Group 2), and 10 solid mammary AdCCs with basaloid features (Group 3). Tissue samples were processed and tested using various molecular techniques, and the Wilcoxon signed-rank test was used to compare the different groups. Molecular data were obtained for both common and rare cases of sinonasal, salivary, and mammary AdCCs, revealing differences in molecular features depending on the tumor’s location. The molecular profile of the AdCCs in the experimental group varied depending on the site, with MYB gene rearrangements being common in all cases. We report the first MYB::KMT2C/D fusions in a subset of salivary AdCCs and sinonasal AdCCs but not in mammary adenoid cystic carcinoma with basaloid features. We conclude that co-occurring genetic alterations may vary among different sites and may have implications for the prognosis and treatment plan of AdCC. More research is needed to fully understand the mechanisms of KMT2C and KMT2D mutations in the development and progression of head and neck cancer, including their interactions with the NOTCH pathway. Full article

Basaloid squamous cell carcinoma (BSCC) is a subtype of squamous cell carcinoma (SCC) associated with a poor prognosis. Tumor–stroma ratio (TSR) has been introduced as a prognostic feature in many solid tumors. TSR was investigated in a series of laryngeal BSCCs and compared with a group of stage-matched conventional SCCs (cSCCs), in both preoperative and surgical specimens, with the intent of ascertaining the more aggressive behavior of BSCC and verifying the presence of stromal-related causes. A series of 14 consecutive laryngeal BSCCs and a control group of 28 stage-matched conventional cSCCs were analyzed. A higher nodal metastasis presence was found in BSCCs (57.1% vs. 28.6%). The recurrence rate was 33.5% and 63.6% in the cSCC and BSCC groups; disease-free survival (DFS) was higher, though not significantly, in patients with cSCC. TSR, large cell nests, and tumor budding showed a moderate to very good agreement, and stroma type a good to very good agreement between biopsies and surgical specimens in the cSCC group. In the BSCC group, agreement was poor to very good for TSR and stroma type, and good to very good for large cell nests and tumor budding. Age was the only feature significant in predicting recurrence in the BSCC group (p = 0.0235). In cSCC, TSR low/stroma rich cases, when evaluated on biopsies or surgical specimens, were associated with lower DFS (p = 0.0036; p = 0.0041, respectively). Laryngeal BSCCs showed a lower DFS than cSCCs, even if statistical significance was not reached. TSR, evaluated in laryngeal biopsies and excised tumors, was prognostic in terms of DFS in cSCC but not in BSCC cases. Full article

Pilomatrix-like high-grade endometrioid carcinoma (PiMHEC) has recently been described as an aggressive variant of endometrial carcinoma. Herein, we described a case of ovarian PiMHEC, comparing it to endometrial PiMHEC and assessing previously published cases of putative ovarian PiMHEC. A 65-year-old woman underwent hysterectomy for an ovarian tumor characterized by solid nests of basaloid cells with prominent ghost cell keratinization. Immunohistochemistry showed nuclear β-catenin and CDX2 expression and loss of estrogen and progesterone receptors and PAX8. These features were consistently observed in all previously published cases and may represent diagnostic criteria of PiMHEC. Other frequent features were geographic necrosis and a low-grade endometrioid component. CK7, neuroendocrine, and basal/squamous markers were inconsistently expressed. All cases with available follow-up showed poor prognosis. PiMHEC should be distinguished from mimickers, such as high-grade endometrioid carcinoma with geographic necrosis, low-grade endometrioid carcinoma with ghost cell keratinization, and undifferentiated/dedifferentiated carcinoma. In conclusion, PiMHEC can also occur in the ovary and shows several consistent clinical, morphological, and immunophenotypical features. These features support that PiMHEC is a distinct entity requiring an aggressive management. Full article

An aetiological role of human papillomavirus (HPV) and/or human polyomaviruses (HPyVs) has been proposed in adenoid cystic carcinoma (AdCC). Moreover, HPV-related multiphenotypic carcinoma (HMSC) was recently introduced as an emerging entity of the sinonasal region. Here, we primarily want to study the role of HPV/HPyV in a large AdCC cohort and, secondly, possibly identify and characterize HMSC. Tumour DNA from 68 patients initially diagnosed with AdCC between 2000 and 2012 was, therefore, tested for 27 HPV types and 10 HPyVs. HPV DNA-positive samples were micromorphologically re-evaluated, further stained for p16^INK4a, S100, p63 and CD117 and tested for the presence of the MYB-NFIB fusion transcript. Notably, no samples were HPyV-positive, while one sinonasal and two tonsillar carcinomas were HPV- and p16-positive. After re-evaluating the micromorphology, immunohistochemistry and presence of fusion transcripts, all tumours had the same appearance and fitted within the diagnosis of HMSC, but in all these three cases, the morphology of the HMSC and basaloid squamous cell carcinoma was overlapping. We conclude that HPV and HPyV have no major role in AdCC. However, based on our data, we also suggest that HMSC should be considered as a basaloid variant of squamous cell carcinoma, and not its own entity, until better characterized. Full article

Adenoid cystic carcinoma/basaloid cell carcinoma of the prostate (ACC/BCC) is a very rare variant of prostate cancer with uncertain behavior. Few cases are reported in the literature. Data on treatment options are scarce. The aim of our work was to retrospectively review the published reports. Thirty-three case reports or case series were analyzed (106 patients in total). Pathological features, management, and follow-up information were evaluated. Despite the relatively low level of evidence given the unavoidable lack of prospective trials for such a rare prostate tumor, the following considerations were made: prostate ACC/BCC is an aggressive tumor often presenting with locally advanced disease and incidental diagnosis occurs during transurethral resection of the prostate for urinary obstructive symptoms. Prostate-specific antigen was not a reliable marker for diagnosis nor follow-up. Adequate staging with Computed Tomography (CT) scan and Magnetic Resonance Imaging (MRI) should be performed before treatment and during follow-up, while there is no evidence for the use of Positron Emission Tomography (PET). Radical surgery with negative margins and possibly adjuvant radiotherapy appear to be the treatments of choice. The response to androgen deprivation therapy was poor. Currently, there is no evidence of the use of truly effective systemic therapies. Full article