"Bone in the penis" or fasciitis ossificans of the penis - a first time description of a pseudo-tumor at an extraordinary site.

BACKGROUND: Fasciitis ossificans is a rare subtype of nodular fasciitis, a benign soft tissue tumor with reactive characteristics. Due to its rapid growth, it is often misdiagnosed as a malignant tumor. While fasciitis ossificans commonly originates from the subcutaneous tissue and can appear throughout the body, it may also arise from extraordinary sites. CASE PRESENTATION: We report the first-ever documented case of fasciitis ossificans arising from the penis in a male patient who presented with a tumor on the glans penis. The tumor was surgically resected due to suspicion of penile cancer. Initial histopathological analysis led to a misdiagnosis of squamous cell carcinoma. However, pathological consultation ultimately confirmed the diagnosis of fasciitis ossificans of the penis originating from the glans penis by demonstrating ossification. CONCLUSION: This case underscores the importance of considering fasciitis ossificans in the differential diagnosis of soft tissue tumors, even in unusual locations such as penile soft tissue.

[A clinical case of piloleiomyoma]. / Klinicheskii sluchai piloleiomiomy.

The article describes a clinical case of a benign tumor from smooth muscle cells - piloleiomyoma. The incidence of leiomyoma in the skin is 3-5% of all leiomyomas. A 27-year-old patient applied to a medical institution with complaints about an intradermal formation in the ear region that occurred repeatedly within 5 months after surgical treatment. After the first surgical intervention, the patient was consulted in various medical organizations, where the following diagnoses were made: «nodular fasciitis¼, «smooth muscle tumor without signs of malignancy¼ and «non-epithelial spindle cell neoplasm¼. According to ultrasound examination, the formation with dimensions of 11×9×5 mm reached the mastoid process of the temporal bone and was characterized by increased internal blood flow. After surgical removal of the neoplasm, taking into account the difficulties of differential diagnosis, an immunohistochemical study was conducted. An accumulation of smooth muscle cells was detected in the surface layers of the dermis under the epidermis by the immunohistochemical study with the use of the marker SMA. A study on CD34 protein revealed a high density of blood capillaries and the absence of its expression in smooth muscle cells. The proliferative index (Ki-67) and mitotic activity (PHH-3) of cells was also studied. The index of proliferative activity was less than 2%, mitoses were isolated. Thus, the results of immunohistochemical study proved the conclusion of piloleiomyoma.

Fasciitis ossificans: imaging features, histology, and differential diagnosis.

AIM: To describe the imaging features of fasciitis ossificans and its histopathological features. MATERIALS AND METHODS: Using a word search of existing pathology reports at the Mayo Clinic, six cases of fasciitis ossificans were identified. The clinical history, histology, and available imaging of the affected area were reviewed. RESULTS: Imaging consisted of radiographs, mammograms, ultrasound images, bone scintigraphs, computed tomography (CT), and magnetic resonance imaging (MRI) images. All cases demonstrated a soft-tissue mass. The characteristic MRI appearance was a T2 hyperintense enhancing mass with surrounding soft-tissue oedema. Peripheral calcifications were seen on radiographs, CT, and/or ultrasound. Histological sections showed distinct zonation, with nodular fasciitis-like zones of myofibroblastic proliferation, which merged with osteoblasts that rim the ill-defined trabeculae of woven bone and became continuous with the mature lamellar bone surrounded by a thin layer of compressed fibrous tissue. CONCLUSION: Imaging features of fasciitis ossificans are that of an enhancing soft-tissue mass located within a fascial plane with prominent surrounding oedema and mature peripheral calcification. Imaging and histology are that of myositis ossificans but occurring within the fascia. It is important that radiologists are aware of the diagnosis of fasciitis ossificans and appreciate its similarity to myositis ossificans. This is particularly important in anatomical locations with fascias but no muscle. Given the radiographic and histological overlap between these entities, nomenclature that encompasses both could be considered in the future.

Unravelling the USP6 gene: an update.

Ubiquitin-specific protease 6 (USP6) rearrangements have been identified in aneurysmal bone cyst, nodular fasciitis, myositis ossificans, fibro-osseous pseudotumour of digits and cellular fibroma of tendon sheath. These entities show clinical as well as histological overlap, suggesting they are all clonal neoplastic belonging to the same biological spectrum and referred to as 'USP6-associated neoplasms'. They all show a characteristic gene fusion formed by juxtaposition of the USP6 coding sequences to the promoter regions of several partner genes, leading to USP6 transcriptional upregulation.

Case report: Large-size intramuscular nodular fasciitis, a challenging histopathologic diagnosis confirmed by molecular detection of USP6 gene rearrangement: Case report and literature review.

The intramuscular subtype of nodular fasciitis (NF) is rare with lesions normally not more than 2 cm in size and characterized by pseudosarcomatous morphology. We report a case of a 27-year-old man with a large-size intramuscular NF. The patient came for treatment complaining of an increasingly enlarged mass in the left upper arm for 4 months. Magnetic resonance imaging (MRI) confirmed the presence of a well-defined tumor measuring 5 cm within the outer edge of the middle humerus. Microscopically, the neoplasm was rich in fibroblasts and myofibroblasts in an interlaced pattern with high mitotic index and evident multinuclear giant cells. Erythrocyte extravasation was easily seen in the stroma. The tumor border was infiltrative. Immunohistochemically, the tumor cells were positive for smooth muscle actin (SMA) and negative for cytokeratin, desmin, H-Caldesmon, CD34, S100, ALK, and ß-catenin. Fibrosarcoma was highly suspected by histopathological and immunohistochemical examination. Molecular detection demonstrated evidence of ubiquitin-specific peptidase 6 (USP6) gene rearrangement in this tumor. Based on the findings, the tumor was diagnosed as intramuscular NF. At 56 months after the initial surgery, the patient had recovered with no evidence of recurrence or metastasis. Large-size intramuscular NF is very rare and easily overdiagnosed as malignant tumor due to its obvious pseudosarcomatoid pathological features. USP6 gene rearrangement detection can effectively avoid this major misdiagnosis.

Eosinophilic Fasciitis: Current and Remaining Challenges.

Eosinophilic fasciitis (EF), defined as diffuse fasciitis with eosinophilia by Shulman in 1974, is a disease with unknown etiology and whose pathogenesis is still being researched. The diagnosis is based on the clinical aspects (skin induration with an "orange peel" appearance), the lab results (eosinophilia, increased inflammatory markers), the skin biopsy with the pathognomonic histopathological result, as well as the typical MRI changes. The treatment includes glucocorticoids and immunosuppressive drugs. Due to severe refractory cases, the treatment remains a challenge. EF is still a disease with potential for further research.

GLUT-1 expression is helpful to distinguish myxofibrosarcoma from nodular fasciitis.

Myxofibrosarcoma (MFS) is a fibroblastic/myofibroblastic neoplasm with a variably myxoid stroma. Histologically, MFS shows a wide spectrum of cellularity, pleomorphism and proliferative activity. Because of its variable morphology and lack of discriminatory markers, MFS can be difficult to distinguish from some benign soft-tissue tumors, especially nodular fasciitis (NF). Glucose transporter 1 (GLUT-1) is expressed in a variety of malignant mesenchymal tumors. In the current study, we evaluated GLUT-1 expression to determine its value in distinguishing MFS from NF. Tissue specimens from 14 MFS cases and 16 NF cases were sectioned and stained for GLUT-1 using immunohistochemistry. The percentage of GLUT-1-positive cells was scored as follows: 0 (no staining), 1+ (1-19%), 2+ (20-50%) and 3+ (>50%). Samples with a score of 1+ were defined as GLUT1-expressing samples. GLUT-1 expression was seen in all 14 MFS cases, whereas only 6 NF cases (37.5%) were positive for GLUT-1 and were scored 1+. Notably, 2-3+ GLUT-1 expression was found in 86% of MFS cases and 0% of NF cases. Our results indicate that GLUT-1 is a highly sensitive immunohistochemical marker for MFS and may be useful for the differential diagnosis of MFS and NF.

Childhood proliferative fasciitis of the orbit mimicking sarcoma: a case report.

Proliferative fasciitis (PF) is a benign fibroblastic reaction with histological and clinical characteristics that overlap with those of malignant soft tissue tumors; thus, it is referred to as a pseudosarcomatous reaction. It continues to be an important cause of diagnostic error and overtreatment. The childhood PF subtype has some distinct histological and immunohistochemical characteristics that make differential diagnosis with malignant tumors even harder, especially with sarcoma. These proliferations generally occur in the lower limbs, and the periorbital region is a rare location of appearance. Here, we describe a case of childhood subtype PF in a 16-year-old girl located in the periorbital area. To the best of our knowledge, this is the first reported case of childhood subtype PF in the periorbital area, and the third case if PF subtypes are not taken into account.

Pathology Clinic: Nodular Fasciitis Involving the External Ear.

Nodular fasciitis is a rare, benign lesion characterized by the pseudosarcomatous proliferation of fibroblasts and myofibroblasts. Accurate diagnosis presents a unique challenge for otolaryngologists, as nodular fasciitis frequently mimics malignancy clinically; however, it can be distinguished from malignancy by subtle findings on pathology. A diagnosis of nodular fasciitis should be considered for any irregular or rapidly growing lesion of the head and neck area, as accurate diagnosis is particularly important to avoid overtreatment in cosmetically sensitive regions.

Multimodality imaging features of USP6-associated neoplasms.

Since the discovery of USP6 gene rearrangements in aneurysmal bone cysts nearly 20 years ago, we have come to recognize that there is a family of USP6-driven mesenchymal neoplasms with overlapping clinical, morphologic, and imaging features. This family of neoplasms now includes myositis ossificans, aneurysmal bone cyst, nodular fasciitis, fibroma of tendon sheath, fibro-osseous pseudotumor of digits, and their associated variants. While generally benign and in many cases self-limiting, these lesions may undergo rapid growth, and be confused with malignant bone and soft tissue lesions, both clinically and on imaging. The purpose of this article is to review the imaging characteristics of the spectrum of USP6-driven neoplasms, highlight key features that allow distinction from malignant bone or soft tissue lesions, and discuss the role of imaging and molecular analysis in diagnosis.

Histopathogenesis of bone- and soft-tissue tumor spectrum with USP6 gene rearrangement: multiple partners involved in the tissue repair process.

Primary aneurysmal bone cyst, nodular fasciitis, myositis ossificans and related lesions as well as fibroma of tendon sheath are benign tumors that share common histological features and a chromosomal rearrangement involving the ubiquitin-specific peptidase 6 (USP6) gene. The tumorigenesis of this tumor spectrum has become complex with the identification of an increasing number of new partners involved in USP6 rearrangements. Because traumatic involvement has long been mentioned in the histogenesis of most lesions in the USP6 spectrum and they morphologically resemble granulation tissue or callus, we attempted to shed light on the function and role USP6 partners play in tissue remodelling and the repair process and, to a lesser extent, bone metabolism.

[Solitary dorsal paravertebral tumor: radiological and histopathological characterization of a pediatric case of nodular fasciitis].

Nodular fasciitis is a benign soft tissue lesion with rapid fibroblastic or myofibroblastic proliferation, rarely observed in pediatric patients. Here, we present the case of a seven-year-old boy with no relevant medical records, in whom an asymptomatic dorsal tumor was incidentally identified. Magnetic resonance imaging showed a left dorsal paravertebral lesion with hypointensity on T1, hyperintensity on T2, peripheral contrast enhancement, and the so-called fascial tail sign. Complete surgical resection of the lesion was achieved. The histopathological study showed a proliferation of spindle or stellate cells with nuclei without atypia in a myxoid or collagenized stroma. The immunohistochemical profile showed positivity for smooth muscle actin, muscle-specific actin antibody HHF35, and calponin. The lesion was diagnosed as nodular fasciitis, an entity with broad and complex differential diagnosis. Presence of specific radiological signs and adequate immunohistochemical characterization of the lesion help perform an accurate diagnosis.

Nodular Fasciitis and Myxolipoma of the Larynx: A rare case report with brief literature review.

Nodular fasciitis (NF) is a peculiar, rapid-growing soft tissue lesion, typically appearing in subcutaneous tissue. Approximately 20% of NF occurs in the head and neck region, where they can involve any anatomic site. Laryngeal involvement, however, is quite rare. Lipoma is recognised as a slow growing, benign mesenchymal tumour; myxolipoma is a rare variant which has a prominent myxoid background. Laryngeal lipoma is infrequent, accounting for only 0.6% of all benign laryngeal lesions. We report a 61-year-old male patient with laryngeal nodular fasciitis coexisting with myxolipoma who presented to a tertiary care hospital in Ar Ramtha, Jordan, in 2020. Radiological and histological findings were indicative of laryngeal nodular fasciitis and myxolipoma was incidentally diagnosed. Following trans-oral debulking of the lesion the mass enlarged rapidly and the patient underwent a tracheostomy with complete mass excision and right partial laryngectomy through an open surgical approach. The patient had an uneventful recovery with no evidence of recurrence. The purpose of this report is to broaden the differential diagnosis of rapid-growing laryngeal masses that cause airway obstruction and to stress the significance of integrative interdisciplinary collaboration to establish an accurate diagnosis, thereby allowing proper management for benign pathologies and avoid futile aggressive treatment.

[Eosinophilic dermatoses]. / Eosinophile Dermatosen.

Eosinophilic dermatoses are a heterogeneous group of rare diseases that histopathologically display the defining pattern of an eosinophil-rich dermal infiltrate. In these eosinophilic dermatoses, a histopathologic pattern called flame figures, which result from degranulation of eosinophils in the tissue, can be observed. Although eosinophil granulocytes can also be detected in other dermatoses such as atopic dermatitis, urticaria, prurigo and bullous pemphigoid, the eosinophil-rich infiltrate is decisive for classic eosinophilic dermatoses. Accordingly, eosinophilic dermatoses include hypereosinophilic syndrome, eosinophilic fasciitis, granuloma faciale, pustular sterile eosinophilia, and angiolymphoid hyperplasia with eosinophilia. These eosinophilic dermatoses display clinical different patterns and are discussed in this article, as well as the interesting eosinophils and novel therapeutic options.

Cranial Fasciitis in Children: Expanding the Spectrum of USP6-Associated Clonal Transient Neoplasms.

Background: Cranial fasciitis (CF) is a benign (myo)fibroblastic proliferation of children. Typical presentation consists of a rapidly growing solitary mass on the temporal or parietal cranium in the first 2 years of age. CF is characterized by a rapid growth followed by a relative slowdown and even growth arrest. The finding of somatic USP6 gene rearrangements demonstrating clonality in CF together with its clinical behavior places it in the category of diseases recently termed "transient neoplasia."Methods: Histological, immunohistochemical, and molecular findings of 18 patients with CF were retrospectively studied.Results: The tumor typically presented as a painless rapidly enlarging mass in the temporal region. Sixty-six percent of the cases harbored USP6 gene rearrangement. Nine patients were treated with gross total resection (GTR) and 9 with subtotal tumor resection (STR). Two patients treated with GTR had recurrence. Five patients treated with STR had progression-free disease for at least 10 months after surgery and in four patients the tumor regressed spontaneously a median 16 months after surgery.Conclusions: In this largest series to date, we reported the clinicopathological, immunohistochemical, and molecular findings of 18 pediatric cases of CF with emphasis on the clinical growth pattern of these tumors.

Application of ultrasound in a case of eosinophilic fasciitis mimicking stiff-person syndrome.

Eosinophilic fasciitis (EF) is a rare disorder characterized by muscle stiffness mimicking other neuromuscular diseases. The diagnosis of EF is made on the basis of typical skin lesions. We report a case of a 36-year-old male patient with suspected stiff-person syndrome (SPS), who presented with progressive limb muscle stiffness and limited mobility of both wrists without obvious skin changes. Ultrasound revealed fascial thickening of bilateral upper and lower limb muscles and enlargement of hypoechoic tissues around the flexor digitorum tendons of the wrist. Skin and fascia biopsy confirmed the diagnosis of EF. Prednisolone therapy resulted in the improvement of muscle stiffness and tightness. Our findings suggest the need to consider connective tissue diseases such as EF in a patient with atypical features of SPS. Ultrasound is helpful for visualizing the causes of muscle stiffness and joint contractures in EF patients.

[Clinicopathological and molecular genetic characteristics of nodular fasciitis in unusual sites].

Objective: To study the clinicopathological, immunophenotypic and molecular genetic characteristics of nodular fasciitis (NF) in unusual sites. Methods: A total of 50 cases of NF diagnosed between January 2015 and January 2021 were reviewed in the Department of Pathology, Henan Provincial People's Hospital, and the clinical and pathologic data were analyzed. Among them, 14 cases from unusual sites were included in this study. Immunohistochemical (IHC) staining was used to detect the expression of related proteins, and fluorescence in situ hybridization (FISH) was used to detect the breakage of the USP6 gene. Results: There were seven males and seven females in the 14 NF respectively. The lesions were located in the extremities, perineum, breast, wrist joints, the gap between lumbar vertebra 4/5, and in eight cases there was involvement of unusual tissues (six cases in skeletal muscle, one case in nerve root, and one case was intravascular). The tumor boundary was unclear with infiltrating growth. Spindle-shaped myofibroblasts were arranged in bundles or chaotically, with mild pleomorphic, small nucleoli and various mitotic figures. The tumor stroma showed collagenization to myxoid degeneration with erythrocyte extravasation and infiltration of inflammatory cells. IHC staining showed that the spindle cells expressed SMA focally or partially, and p16 diffusely and strongly. FISH showed that 12 of 14 cases had USP6 gene breakage, and two of them occurred in the intrathoracic skeletal muscle with the red signal amplification of USP6 gene. Conclusions: NF in unusual sites shows similar clinicopathological and genetic characteristics to classic NF, but the tumor mostly has infiltrating borders, non-specific and strong expression of p16, and USP6 red signal amplification. The pathological diagnosis of NF in rare sites should be highly vigilant.

Pulmonary inflammatory myofibroblastic tumor coexisting with lymphangitis carcinomatosis: Mimicking metastatic papillary thyroid carcinoma with nodular fasciitis-like stroma.

Inflammatory myofibroblastic tumors (IMTs) are uncommon; intermediate grade soft tissue tumors occurring in young individuals with an uncertain behaviour. The incidence of pulmonary lymphangitis carcinomatosis (PLC) is around 6-8% of all pulmonary metastases. However, PLC due to papillary thyroid carcinoma (PTC) is very uncommon. We present a case of a 26-year-old male, who presented with a solitary left lung nodule on radiological scans. There was also a past history of thyroid surgery done two years back for PTC. Histology revealed a soft tissue tumor reminiscent of IMT. The periphery of the IMT nodule showed metastatic PTC in the form of extensive PLC. In view of this unusual histology, a diagnosis of PTC with nodular fasciitis-like stroma (PTC-NFS) was initially considered. However, molecular studies for anaplastic lymphoma kinase (ALK) gene rearrangement confirmed the diagnosis of IMT. This case highlights the unusual occurrence of tumor-to-tumor metastasis causing diagnostic challenges and also the importance of molecular testing.

USP6 rearrangement in pediatric nodular fasciitis.

Nodular fasciitis (NF) is a myofibroblastic proliferation that is uncommonly present in pediatric patients. These benign neoplasms can masquerade as more insidious sarcomatous proliferations on both clinical exam and initial histopathologic review, often prompting undue concern in patients, parents, and providers. While immunohistochemical analysis of NF can be variable, adding to the diagnostic uncertainty, molecular analysis documenting ubiquitin-specific protease 6 (USP6) gene rearrangement can help confirm the diagnosis as an association between NF and USP6 overexpression was first identified 10 years ago in an analysis that found rearrangements of the involved locus in over 90% of studied samples. In this report, we review one case of NF located on the chin of a nine-year-old girl in which molecular testing was essential to secure the correct diagnosis, and provide a summary of documented cases of USP6 overexpression in transient pediatric neoplasms.