Intracerebral benign fibrous histiocytoma.

Benign fibrous histiocytoma (BFH) within the intracerebral region is remarkably rare. Our report details 2 cases of unusual BFH instances that exhibit no adhesion to the dura mater or cerebral falx, accompanied by a comprehensive literature review. While magnetic resonance imaging demonstrates specific characteristics for BFH, it does not readily differentiate BFH from more common brain neoplasms like gliomas and metastatic tumors. The definitive diagnosis of BFH depends primarily on histopathological and immunohistochemical examinations. Total surgical resection is considered an efficacious therapeutic approach, emphasizing the necessity for prolonged postoperative surveillance to detect any potential tumor recurrence or metastasis.

Giant thigh hemosiderotic/aneurysmal dermatofibroma: Case report with radiologic-pathologic correlation.

Hemosiderotic/aneurysmal variant of dermatofibroma (DF) is infrequent and may be misdiagnosed with malignant lesions. We report the case of a giant (7.6cm) subcutaneous hemosiderotic/aneurysmal DF (H/ADF) of the thigh in a 53-year-old female patient. Internal arterial and venous hypervascularity was seen by spectral Doppler ultrasound. Magnetic resonance image showed a discrete homogeneous hypointense in T1-weighted images (WI) and T2-WI mass, with hyperintense areas in fat-suppressed T2-WI. The histology revealed a monotonous fusocelular proliferation without atypia, positive for CD163, factor XIIIa and CD10. Widely distributed hemosiderin pigment and two blood-filled pseudovascular spaces lacking endothelial lining were present. H/ADF was diagnosed. The mass was removed but surgical margins were affected. The patient did not present local relapse or distant metastasis. H/ADF are unusual cutaneous soft tissue tumours that can be clinically, radiologically and histopathologically confused with malignant lesions such as melanomas, vascular lesions or sarcomas, especially in giant cases.

Sclerosing angiomatoid nodular transformation of the spleen: Case reports and literature review.

RATIONALE: Sclerosing angiomatoid nodular transformation (SANT) of the spleen is an uncommon benign vascular lesion with an obscure etiology. It predominantly affects middle-aged women and presents with nonspecific clinical signs, making preoperative diagnosis challenging. The definitive diagnosis of SANT relies on pathological examination following splenectomy. This study aims to contribute to the understanding of SANT by presenting a case series and reviewing the literature to highlight the clinical presentation, diagnostic challenges, and treatment outcomes. PATIENT CONCERNS: In this retrospective study, we analyzed the clinical data of 3 patients with confirmed SANT admitted from November 2013 to October 2023. The cases include a 25-year-old male, a 15-year-old female, and a 39-year-old male, each with a splenic mass. DIAGNOSES AND INTERVENTIONS: All of the three cases were treated by laparoscopic splenectomy (LS). Pathological examination confirmed SANT in all cases. OUTCOMES: No recurrence or metastasis was observed during a 10-year follow-up for the first 2 cases, and the third case showed no abnormalities at 2 months postoperatively. Despite its rarity, SANT is a significant condition due to its potential for misdiagnosis and the importance of distinguishing it from malignant lesions. The study underscores the utility of LS as a safe and effective treatment option. LESSONS: SANT is a rare benign tumor of the spleen, and the preoperative diagnosis of whom is challenging. LS is a safe and effective treatment for SANT, with satisfactory surgical outcomes and favorable long-term prognosis on follow-up. The study contributes to the limited body of research on this rare condition and calls for larger studies to validate these findings and improve clinical management.

Radiation Therapy-Induced Fibrous Histiocytoma, Mimicking Local Recurrence and Detected by 18 F-FDG PET/CT in a Patient With Breast Cancer.

ABSTRACT: A 76-year-old woman was diagnosed breast carcinoma and treated with breast-conserving surgery and chemoradiotherapy. A year after the treatment completion, restaging 18 F-FDG PET/CT scan detected no any pathological finding. However, due to a lesion detected during physical examination on the right thoracic wall adjacent to the primary tumor bed, 18 F-FDG PET/CT imaging was performed 9 months later for restaging. Highly intense FDG uptake was detected in an approximately 1-cm nodular lesion, and metastasis was reported as suspicious, and histopathological confirmation was recommended. Excision was performed and pathological examination diagnosed benign cellular fibrous histiocytoma.

Metastasizing aneurysmal dermatofibroma initially diagnosed as angiosarcoma confirmed by CD63::PRKCD fusion gene detection with nanopore sequencing.

Dermatofibroma (DF) is a benign tumor that forms pedunculated lesions ranging in size from a few millimeters to 2 cm, usually affecting the extremities and trunks of young adults. Histopathologically, DF is characterized by the storiform proliferation of monomorphic fibroblast-like spindle cells. In addition to neoplastic cells, secondary elements such as foamy histiocytes, Touton-type giant cells, lymphoplasmacytes, and epidermal hyperplasia are characteristic histological features. Several histological variants, including atypical, cellular, aneurysmal, and lipidized variants, have been reported; cases with variant histologies are sometimes misdiagnosed as sarcomas. We present a case of metastasizing aneurysmal DF that was initially diagnosed as an angiosarcoma on biopsy. A 26-year-old woman was referred to our hospital with a gradually enlarging subcutaneous mass in her lower left leg. Positron emission tomography-computed tomography revealed high fluorodeoxyglucose uptake not only in the tumor but also in the left inguinal region. On biopsy, ERG and CD31-positive atypical spindle cells proliferated in slit-like spaces with extravasation, leading to the diagnosis of angiosarcoma. Histology of the wide-resection specimen was consistent with DF, and lymph node metastasis was also observed. Nanopore DNA sequencing detected CD63::PRKCD fusion and copy number gain, although CD63 was not included in the target region of adaptive sampling. This report highlights the importance of recognizing the unusual clinical, radiological, and pathological features of DF to avoid misdiagnosis, and the potential diagnostic utility of nanopore sequencer.

A Tale of Two Tumors: A Collision Tumor of Atypical Fibroxanthoma and Basal Cell Carcinoma.

ABSTRACT: A collision tumor is an infrequent phenomenon characterized by the presence of 2 histologically distinct tumor types (either benign or malignant) occurring within the same specific anatomical site. We describe a rare case of co-occurrence of basal cell carcinoma and atypical fibroxanthoma presenting as a single lesion on the scalp in a 76-year-old man. The lesion was clinically suspicious for basal cell carcinoma and biopsied. Histologic examination showed 2 distinct tumors, one with basaloid cells and the other one with pleomorphic spindle cells colliding and growing together. Immunohistochemical stains were crucial in establishing the diagnosis. This presentation is exceedingly rare and requires additional evaluation for diagnosis.

Primary Pulmonary Myxoid Sarcoma and Thoracic Angiomatoid Fibrous Histiocytoma: Two Sides of the Same Coin?

Primary pulmonary myxoid sarcoma (PPMS) and thoracic angiomatoid fibrous histiocytoma (AFH) are rare neoplasms with EWSR1 fusions and overlapping morphology. Both tumor types often show epithelial membrane antigen expression, but AFH characteristically co-expresses desmin. We encountered a case of PPMS with the unexpected finding of patchy, strong anaplastic lymphoma kinase (ALK) (previously reported in AFH) and synaptophysin expression. We evaluated a cohort of PPMS and thoracic AFH with systematic morphologic comparison and surveyed for aberrant expression of ALK and synaptophysin. Medical records and slides were reviewed for 16 molecularly confirmed cases of PPMS (n=5) and thoracic AFH (n=11). Each case was scored for morphologic characteristics typical of PPMS and/or AFH. ALK, synaptophysin, chromogranin, desmin, and epithelial membrane antigen immunostains were performed on cases with available tissue. AFH and PPMS cases showed similar age at presentation and long-term tumor behavior. Almost all cases of PPMS and AFH had a fibrous pseudocapsule and lymphoid rim. All PPMS had myxoid stroma and reticular growth pattern, but these features were also present in a subset of AFH. Synaptophysin expression was present in 6 of 11 AFH and 1 of 5 PPMS; all tested cases were negative for chromogranin (n=15). One case of AFH and 1 case of PPMS showed focally strong coexpression of synaptophysin and ALK. AFH and PPMS show considerable clinicopathologic overlap. When supportive, the immunohistochemical findings described may aid in diagnosis before molecular confirmation. PPMS and AFH may be morphologic variants of the same clinicopathologic entity, which can show more immunophenotypic variability than previously reported.

Pediatric dermatofibromas: Truncal predominance in younger children.

Pediatric dermatofibromas are considered rare in young children and have not been well characterized, often misdiagnosed clinically. We performed a retrospective case series of children younger than 18 years with histopathologically diagnosed dermatofibromas at our institutions and evaluated age at onset and diagnosis, sex, lesion location, and size, associated symptoms, change over time, and pre-biopsy diagnosis. Overall, dermatofibromas were most common on the back and chest (20/53; 38%), followed by the legs (15/53; 28%) and arms (12/53; 23%) with the most common pre-biopsy diagnosis of "cyst" (23/53; 43%), followed by dermatofibroma (16/53; 30%), and pilomatricoma (12/53; 23%). Our study reinforces previous findings of truncal predominance of pediatric dermatofibromas, different from adults.

Clinicopathological analysis of sclerosing angiomatoid nodular transformation in the spleen.

Background: Splenic sclerosing angiomatoid nodular transformation (SANT) is a rare benign nodular lesion in the red medulla of the spleen. In the past, SANT has not been consistently recognized as the name for this condition and was often misdiagnosed for other conditions. In recent years, SANT has been acknowledged by most scholars as multiple reports have been published. Aim: To assess the clinicopathological features of SANT to identify the histological characteristics of SANT to improve diagnosis and clinical treatment. Materials and Methods: We assessed 25 cases of SANT diagnosed at Zhongshan Hospital affiliated with Fudan University from September 2014 to October 2021, including 14 men and 11 women, aged 24-62 years old. Results: Fourteen cases were complicated with benign tumors of the liver, pancreas, kidney, uterus, and prostate. One case was complicated with renal clear cell carcinoma, and one was complicated with hepatocellular carcinoma. The gross neoplasm is multinodular and well defined. Histologically, angiomatoid nodules are composed of fattened, round, or irregular blood vessels, with or without red blood cells in the lumen, with unequal red blood cell extravasation, and fibrocytes around the nodules. The hemangiomatous nodules were positive for CD31 and CD34, while the vascular wall smooth muscle cells and fibrocytes around the nodules were positive for SMA. Conclusion: The diagnosis of SANT requires a combination of immunohistochemical and histological features, and early splenectomy is crucial for treatment.

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.

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.

Kinase expression in angiomatoid fibrous histiocytoma: panTRK is commonly expressed in the absence of NTRK rearrangement.

Angiomatoid fibrous histiocytoma (AFH) is a soft tissue tumour of intermediate (rarely metastasising) malignant potential, which harbours EWSR1/FUS gene fusions. These tumours can express anaplastic lymphoma kinase (ALK) in the absence of gene rearrangement or copy number alteration and can also coexpresses Pan-TRK immunohistochemistry (IHC). All EWSR1/FUS-rearranged AFH were retrieved from the files of three institutions and Pan-TRK (EPR17341), ALK and BRAF V600E IHC were performed. Fourteen AFH cases were identified, which included three cases of intracranial mesenchymal tumours with FET-CREB fusions. PanTRK and ALK positive immunostaining was identified in 9 (64.2%) and 12 (85.7%) cases, respectively. No NTRK or ALK translocations or increased copy number/amplification were identified in all eight cases which had fluorescence in situ hybridisation and/or next generation sequencing for NTRK1-3 and ALK available for assessment. None of the cases expressed BRAF-V600E.Although our study is limited, our report is the first to document PanTRK expression in AFH in the absence of identifiable NTRK1-3 gene alterations.

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.

A study of collagen refractility in dermatofibroma and dermatofibrosarcoma protuberans using diffractive microscopy.

BACKGROUND: Diffractive microscopy creates contrast within samples that are otherwise uniform under bright light. This technique can highlight subtle differences in refractive indices within birefringent samples containing varying amounts of mature collagen. Dermatofibroma (DF) and dermatofibrosarcoma protuberans (DFSP) possess differences in their mature collagen content and, therefore, may be distinguishable using diffractive microscopy. METHODS: Two hundred forty-two DF and 85 DFSP hematoxylin-eosin (H&E)-stained specimens were analyzed using diffractive microscopy. Data regarding the distribution pattern and strength of refractility was recorded. RESULTS: DFSP was more frequently found to be focally, weakly, or non-refractile (82.9%; n = 68) under diffractive microscopy, while DF more often showed diffusely bright refractility (52.9%; n = 128). DFSP samples with diffuse refractility in portions of the lesion (17.1%; n = 14) also exhibited a unique checkerboard pattern distinct from that which was seen in DF samples. CONCLUSIONS: The absence of diffuse refractility was more closely associated with DFSP, as was the presence of a unique checkerboard diffraction pattern. Despite high sensitivity (Sn = 82.9%), absent refractility was not a specific test (Sp = 52.9%), with 47.1% (n = 114) of DF samples sharing this feature. The distinction between DF and DFSP is often diagnosed using H&E alone. In difficult cases, examination of collagen under diffractive microscopy may be useful in distinguishing DFSP from DF and provide an alternative cost-effective tool to immunohistochemical staining.