Histopathological and Ultrastructural Study of a Canine Langerhans Cell Tumour (Canine Cutaneous Histiocytoma).

Canine cutaneous histiocytoma (CCH) represents a significant proportion of dog skin tumours, often manifesting as the most common neoplastic skin condition in young animals. Predominantly affecting dogs under four, these tumours appear primarily as solitary lesions that may regress spontaneously. This study, conducted over five years at the University of Trás-os-Montes e Alto Douro, involved a detailed histopathological and ultrastructural examination of 93 CCH cases. Histologically, these tumours showed distinct patterns of lymphoid infiltration, which contributed to their classification into four groups based on the inflammatory response and histological architecture. Most tumours displayed signs of epidermal invasion and frequent mitotic figures, with necrosis present in over half of the cases. Ultrastructurally, the neoplastic cells were characterised by pleomorphism, abundant organelles, and adherens-type junctions. This study offers significant insights into the pathophysiology and morphological characteristics of CCH, underscoring the importance of detailed histological and ultrastructural analysis in accurately diagnosing and understanding this common canine tumour.

Application of 18F-FDG PET/CT imaging in a primary angiomatoid fibrous histiocytoma of pulmonary bronchus: case report and literature review.

Background: Angiomatoid fibrous histiocytoma (AFH) is a clinically rare, low-grade malignant soft tissue tumor that occasionally metastasizes. It accounts for 0.3% of all soft tissue tumors and most frequently occurs in the extremities, followed by the trunk, and the head and neck. Primary angiomatoid fibrous histiocytoma (PAFH) of the pulmonary bronchus is rare. In this paper, the clinical and imaging data of a case of PAFH of the pulmonary bronchus are reported, and the literature is reviewed. Case description: A 57-year-old female patient presented with a six-month history of cough without apparent cause, characterized by paroxysmal dry cough, chest tightness, and shortness of breath, which worsened with activity. She did not experience fever, chills, chest pain, hemoptysis, or night sweats. Laboratory tests revealed an elevated C-reactive protein and ferritin levels, while tumor markers such as AFP, CEA, CA199, CA125, CA50, and T-SPOT were negative. A chest CT scan showed bronchial obstruction, atelectasis, and a soft tissue density in the right middle lobe of the lung. The enhanced scan demonstrated uneven enhancement of endobronchial nodules. An 18F-FDG PET/CT scan revealed a nodular soft tissue density shadow in the right lung bronchus with uneven density, clear boundaries, and increased 18F-FDG uptake, with a maximum standard uptake value (SUVmax) of 11.2. Bronchoscopy revealed a nodular or polypoid mass that was yellow and tough. Based on imaging findings, the preoperative diagnosis favored lung cancer. However, the postoperative pathological diagnosis confirmed primary angiomatoid fibrous histiocytoma (PAFH) of the pulmonary bronchus. Conclusion: The incidence of primary angiomatoid fibrous histiocytoma (PAFH) is very low, and its clinical manifestations and imaging findings lack specificity, with the final diagnosis relying on pathology. PET/CT imaging has a certain value in the diagnosis of PAFH and holds significant application value in preoperative staging, postoperative efficacy evaluation, and follow-up monitoring. In conclusion, this case report further expands the spectrum of lung and bronchial tumors.

Clinical and pathological analyses of 14 cases of angiomatoid fibrous histiocytoma.

Angiomatoid fibrous histiocytoma (AFH) is a soft tissue tumor of uncertain differentiation. Although its prognosis is good, its diagnosis and differential diagnosis remain a challenge, particularly for tumors with an atypical morphology. We evaluated the clinicopathological characteristics of 14 AFH cases and examined the key factors in its diagnosis or differential diagnosis. The cohort comprised 6 men and 8 women aged 9-65 years (average age: 31.2 years). Most of the tumors (11/14, 79%) were located in soft tissues, whereas 3/14 (21%) were located in the lung (1 case) and brain (2 cases). Tumor cells were spindle-shaped to epithelioid, with a visible fibrous capsule (9/14, 64%), hemorrhagic gap (9/14, 64%), lymphocyte sleeve (7/14, 50%), necrosis (3/14, 21%), and infiltrative boundary (4/14, 29%). The tumors expressed desmin (10/14, 71%) and exhibited low levels of Ki-67. 13 cases (93%) displayed ESWSR1 gene rearrangement. At follow-up, 1 case (7%) experienced local tumor recurrence. AFH is a rare intermediate tumor. Its pathological diagnosis requires a comprehensive analysis of histological, immunophenotypic, and molecular genetic features to avoid misdiagnosis. Our study has further enriched the histological features of AFH, emphasizing the importance of differential diagnosis and providing a reference for clinical practice.

Immune checkpoint regulation is critically involved in canine cutaneous histiocytoma regression.

Introduction: Canine cutaneous histiocytoma (CCH) is a benign tumor frequently occurring in young dogs which is derived from Langerhans cells (LC). Distinguishing features of this tumor are its spontaneous regression following a rapid tumor growth. Impaired control of immune checkpoints during tumor development and progression is a widespread phenomenon which may result in an absent or ineffective immune response. The interaction between the inflammatory response and the expression of immune checkpoint molecules is only partially described in this tumor type. The aim of this study was to identify immune checkpoint molecules and molecules from the interferon-mediated immune response that are involved in the regression of CCH. Methods: Forty-eight CCH derived from dogs ≤ 4 years of age were assigned to one of four groups according to the severity and distribution of lymphocyte infiltration. Using immunohistochemistry and whole-slide image scans of consecutive sections the expression of programmed death protein ligand 1 (PD-L1), CD80, CD86, Survivin, forkhead box protein 3, Ki-67, cleaved caspase-3, CD3, and mx1 were investigated. RNA in-situ hybridization was performed for transcripts of mx1 and interferon-γ. Results: Neoplastic cells showed an expression of PD-L1, CD80, CD86, and Survivin. The density of CD80 expressing cells was negatively correlated with regression while the density of cleaved caspase-3 positive cells increased with regression. Mx1 transcripts and protein were predominantly localized in neoplastic cells while interferon-γ transcripts were most frequently detected in T-cells. Conclusion: The expression of the immune checkpoint molecules CD86 and PD-L1 and particularly the reduced expression of CD80 in groups 3 and 4 indicate an influence of the investigated immune checkpoints on tumor regression. In parallel an activation of the apoptotic cascade during regression is suggested. Finally, the detection of mx1 within the neoplasm pinpoints to a yet undisclosed role of anti-cellular signaling in tumor immunity.

Sural flap reconstruction of lateral malleolus following undifferentiated pleomorphic sarcoma resection with 1-year follow-up.

We report a case of a 54-year-old female who presents with a gradually expanding mass at the right lateral malleolus. The diagnosis of undifferentiated pleomorphic sarcoma was made after a histopathological examination of the mass following a wide tumor excision. The defected soft tissue area was reconstructed using a local flap, reverse sural artery flap. Following the surgical management, multiple radiotherapy sessions were completed. The patient's follow-up result showed no signs of local recurrence or metastasis, and the wound was well-healed with no complications other than paresthesia in a small area at the posterolateral aspect of the ankle under the lateral malleolus. This case represents a rare form of malignant neoplasm and emphasizes the effectiveness and safety of the reverse sural artery flap reconstruction technique, especially in places where microsurgery is unavailable or when the patient's status does not allow for prolonged anesthesia.

Clinicopathologic and molecular study of superficial CD34-positive fibroblastic tumours mimicking atypical fibrous histiocytoma (dermatofibroma).

AIMS: Superficial CD34-positive fibroblastic tumour (SCD34FT) is an uncommon but distinctive low-grade neoplasm of the skin and subcutis that shows frequent CADM3 expression by immunohistochemistry (IHC). In this study, prompted by an index case resembling 'atypical fibrous histiocytoma (FH)' that was positive for CADM3 IHC, we systematically examined a cohort of tumours previously diagnosed as 'atypical FH' by applying CADM3 and fluorescence in situ hybridization (FISH) for PRDM10 rearrangement, to investigate the overlap between these tumour types. METHODS AND RESULTS: Forty cases of atypical FH were retrieved, including CD34-positive tumours (n = 20) and CD34-negative tumours (n = 20). All tumours were stained for CADM3. All CADM3-positive tumours were evaluated by FISH to assess for PRDM10 rearrangement. Eleven CD34-positive tumours (11/20, 55%) coexpressed CADM3 and were reclassified as SCD34FT. None (0/20) of the CD34-negative atypical FH were CADM3-positive. Reclassified SCD34FT (10/11) arose on the lower extremity, with frequent involvement of the thigh (n = 8). Features suggestive of atypical FH were observed in many reclassified cases including variable cellularity, spindled morphology, infiltrative tumour margins, collagen entrapment, epidermal hyperpigmentation, and acanthosis. Variably prominent multinucleate giant cells, including Touton-like forms, were also present. An informative FISH result was obtained in 10/11 reclassified tumours, with 60% (6/10) demonstrating PRDM10 rearrangement. CONCLUSION: A significant subset of tumours that histologically resemble atypical FH, and are positive for CD34, coexpress CADM3 and harbour PRDM10 rearrangement, supporting their reclassification as SCD34FT. Awareness of this morphologic overlap and the application of CADM3 IHC can aid the distinction between SCD34FT and atypical FH.

Imaging and Clinical Findings of Primary Malignant Fibrous Histiocytoma of the Urinary Bladder: A Case Report.

Primary malignant fibrous histiocytoma (MFH) is a malignant tumor of mesenchymal origin that rarely occurs in the urinary tract, particularly in the urinary bladder. Unlike urothelial carcinoma, which accounts for most bladder cancers, it occurs in the submucosal portion of the bladder wall and consists of the lamina propria, muscularis propria, and adventitia. It is presumed to originate from poorly differentiated pluripotent mesenchymal cells in which fibroblasts and histiocytes are partially differentiated. Radiologically, it is known as the "non-papillary tumor" and is commonly diagnosed as a large mass without necrosis, which shows invasion beyond the muscularis propia. Although the prognosis of this rare malignancy depends on pathological parameters, it generally has a poor prognosis with high local tumor recurrence. Here, we present a case of primary MFH in the urinary bladder with clinical symptoms of lower abdominal pain without gross hematuria that recurred rapidly and showed an aggressive disease course.

Clinical Presentations and Intense FDG-avidity in Pulmonary Angiomatoid Fibrous Histiocytoma with Potential Diagnostic Pitfalls: A Case Report and Literature Review.

INTRODUCTION: Angiomatoid fibrous histiocytoma (AFH) is a borderline tumor usually affecting the the children or young adults. 18F-Fluorodexoyglucose (FDG) positron emission tomography/computed tomography (PET/CT) investigations of pulmonary AFH are rare, and there are currently no reports of intense FDG uptake in AFH. CASE REPORT: We report an AFH that occurred in the lung of a 57-year-old woman. She presented with paroxysmal cough and occasional bloodshot sputum. 18FFDG PET/CT revealed a right parahilar nodule with intense FDG-avidity, middle lobe atelectasis, and several bilateral axillary lymph nodes with mild hypermetabolic activity. This patient underwent a right middle lobe lobectomy via video-assisted thoracoscopy. Histopathologically, the diagnosis was pulmonary AFH. She had an uneventful postoperative course, and the bilateral axillary lymph nodes regressed during postoperative follow-up. CONCLUSIONS: The clinical presentation and image findings of patients with primary pulmonary AFH may be potential diagnosis pitfalls. The diagnosis of lymph nodes or distant metastases should be approached with caution. To avoid misdiagnosis, biopsy with histological examination and immunohistochemichal staining should be performed as early as possible.

[Xanthogranulomatous adrenalitis : A rare and difficult differential diagnosis of adrenal gland tumors]. / Xanthogranulomatöse Adrenalitis : Seltene und schwierige Differentialdiagnose von Nebennierentumoren.

A radiologically diagnosed tumor in a 29-year-old woman with a fever of around 39 °C was operated on under the suspicion of cholecystitis or a liver abscess. A solid tumor was found in the adrenal gland and resected. The frozen section findings did not reveal a clear diagnosis of entity and assignment. Histologically, the tumor was found to consist of densely clustered large histiocyte-like cells with expression of vimentin, CD68, and CD163 as well as negativity for keratin, langerin, and SMA. We diagnosed xanthogranulomatous adrenalitis and discussed the differential diagnoses (Langerhans cell histiocytosis, Rosai-Dorfman disease, malakoplakia, Erdheim-Chester disease).

The devastating impact of unresectable infectious undifferentiated pleomorphic sarcoma in the gluteal region: A case report.

INTRODUCTION AND IMPORTANCE: Undifferentiated pleomorphic sarcoma (UPS), previously known as malignant fibrous histiocytoma (MFH), is a highly aggressive soft tissue sarcoma characterized by its pleomorphic histology and lack of differentiation. CASE PRESENTATION: A 35-year-old man visited our oncology department with a complaint of a growing mass in his left buttock area. The mass had been increasing in size for the past six months, affected by local and systemic infection. While it was initially painless, the patient started feeling discomfort during sitting and physical activities a few weeks, but later the complication of tumor became more aggressive. CLINICAL DISCUSSION: UPS can arise in various anatomical sites, including the extremities, trunk, retroperitoneum, and head and neck region. Clinically, UPS may present as a rapidly growing mass, often with pain and limited range of motion. However, the presentation may vary depending on the site of origin. Treatment for UPS typically involves surgical resection, aiming to remove the tumor completely. Depending on the size, location, and aggressiveness of the tumor, additional treatments such as radiation therapy or chemotherapy may be recommended. CONCLUSION: Undifferentiated pleomorphic sarcoma (UPS) represents a rare and aggressive soft tissue sarcoma requiring prompt and accurate diagnosis for appropriate management. With its non-specific clinical presentation and histological features, UPS can be challenging to differentiate from other soft tissue tumors.

Recurrent benign fibrous histiocytoma of the bone benefits from denosumab followed by malignant transformation: a case report.

Benign fibrous histiocytoma of the bone (BFHB) is a rare mesenchymal tumor, representing less than 1% of all benign bone tumors. This controversial entity is characterized by a mixture of fibroblasts arranged in a storiform pattern, varying amounts of osteoclast-type giant cells and foamy macrophages. Curettage or simple resection is usually curative. However, it was reported that up to 11% of the patients suffer from relapse. Here, we report a case of malignant transformation of BFHB after long-lasting disease stabilization under denosumab therapy.

Pleomorphic Dermal Sarcoma.

Pleomorphic dermal sarcoma (PDS) is a rare cutaneous/subcutaneous neoplasm of purported mesenchymal differentiation that exists along a clinicopathologic spectrum with atypical fibroxanthoma (AFX). While PDS and AFX share histopathologic and immunohistochemical features, PDS exhibits deeper tissue invasion and has a higher rate of metastasis and local recurrence than AFX. Given its aggressive clinical course, early recognition and clinical management of PDS are essential for optimizing patient outcomes. This review aims to provide a brief overview of the clinicopathologic and molecular features, prognosis, and treatment of PDS.

Angiomatoid fibrous histiocytoma: primary intracranial lesion with thoracic spine metastasis and a malignant course. Illustrative case.

BACKGROUND: Angiomatoid fibrous histiocytoma (AFH) is an exceptionally rare soft tissue neoplasm. This tumor primarily presents as a benign soft tissue lesion in children with an average age of 14 years. The standard treatment regimen is wide local excision with interval follow-up. However, newer reports have demonstrated malignant potential with the possibility of intracranial metastasis. OBSERVATIONS: A 45-year-old male with no soft tissue primary tumor presented with a primary intracranial lesion and thoracic spine metastasis refractory to chemotherapy and radiation treatment. LESSONS: This report illustrates the potential for a highly malignant nature of metastatic AFH. In addition, the authors demonstrate an incidence of AFH in a middle-aged male without a primary soft tissue or skin lesion. This report highlights the importance of prompt treatment and excision for AFH, as there is still little understanding of successful options for systemic therapy.

An Unusual Case of an ALK-Negative Epithelioid Fibrous Histiocytoma in the External Auditory Canal.

This article represents the first reported case in the external auditory canal of epithelioid fibrous histiocytoma (EFH), a rare benign cutaneous epithelioid neoplasm. Immunostaining revealed uncommon negative staining for anaplastic lymphoma kinase (ALK) expression. This case and literature review outline the diagnostic strategy for this highly unusual neoplasm. Laryngoscope, 134:3371-3373, 2024.

168 Cases of aneurysmal dermatofibroma and 29 cases of hemosiderotic dermatofibroma: A clinicopathologic study.

OBJECTIVES: Aneurysmal dermatofibroma (ADF) and hemosiderotic dermatofibroma (HDF) are rare variants of dermatofibroma (DF) characterized by distinct histologic features. While HDF is traditionally considered a precursor to ADF, supporting evidence is limited, and the etiology remains unclear. A retrospective analysis of 2128 DF cases (2016-2019) was conducted to investigate the clinicopathologic characteristics of ADF, HDF, and other DFs. METHODS: Histopathologically diagnosed DF cases were examined for ADF and HDF. Univariate analyses were performed to compare clinicopathologic features. RESULTS: Among the cases, 168 (7.9%) were ADF and 29 (1.4%) were HDF. Aneurysmal dermatofibroma and HDF shared several common characteristics, including lower occurrence in females, larger size, and increased cellularity (all P < .0001). Notably, 29% of ADFs lacked hemosiderin deposition. Aneurysmal dermatofibroma primarily manifested on exposed areas (face and forearm, both P < .001). In contrast, 41% of HDFs occurred on the lower leg (P = .018), and all lower leg HDFs exhibited signs of venous stasis, distinguishing them from other HDFs (P < .0001). CONCLUSIONS: Our findings indicate a potential close relationship between ADF and HDF. Contrary to conventional beliefs, we also presented the possibility of ADF progressing into HDFs. Physical trauma may induce ADF, and HDFs may emerge from ADFs in conjunction with venous stasis in the lower extremities.

Recurrent and metastatic cellular cutaneous fibrous histiocytoma: A case report and literature review.

Cutaneous fibrous histiocytoma (FH) is considered a benign dermal tumor. The cellular variant is rare and poorly documented. Besides presenting a high risk of local recurrence, it has a low but serious metastatic potential. We present a case of metastatic cellular FH and also review the literature on this tumor, given its unusual metastatic development. A 47-year-old male patient presented with a lesion in the anterior surface of the right thigh, which has been present since adolescence but had grown during last year. Anatomopathological evaluation revealed a cellular FH, and the lesion was completely removed. Six months later, tumor recurrence with multiple compartment muscle involvement and pulmonary metastasis were detected. Both lesions were completely resected and after 3 years of follow-up, the patient is asymptomatic and free of the disease. We conclude that FH should be carefully sampled to detect variants with high local recurrence rates or with some metastatic risk such as the cellular one. We recommend wide surgical resection and a close follow-up including chest x-rays or thorax computed tomography (CT) in all cellular FH cases with local recurrence.

Angiomatoid Fibrous Histiocytoma of the Chest Wall Protruding into the Thoracic Cavity Mimicking Metastasis in a Patient with Breast Cancer.

Angiomatoid fibrous histiocytoma (AFH) is a rare soft tissue tumor of intermediate malignancy and uncertain differentiation. To date, only four patients diagnosed with AFH located in the chest wall have been described. Herein, we describe a 44-year-old woman diagnosed with breast infiltrating lobular carcinoma. During the imaging study with positron emission tomography-computerized tomography scan, a 4 cm solid lesion located in the chest wall was identified. Fine-needle aspiration followed by surgical excision with intraoperative frozen section study was performed. The combined histomorphologic, immunohistochemical, and molecular findings confirmed the diagnosis of AFH. In this report, we describe, to the best of our knowledge, the first patient with synchronous AFH and breast cancer.