UNASSIGNED: Spindle cell lesions comprise a vast plethora of benign and malignant lesions with similar clinical and radiographic features. Their overlapping histopathologic features ensure a diagnostic dilemma.
UNASSIGNED: The current multicentric study aims to delineate fibroblastic and myofibroblastic oral spindle cell lesions based on cytomorphology and comprehensive immunohistochemical analysis.
UNASSIGNED: The experimental study was conducted at MS Ramaiah University of Applied Sciences, Bangalore, and All India Institute of Applied Sciences, Delhi.
UNASSIGNED: A comprehensive histological scoring criteria and panel of immunohistochemical makers (STAT6, CD31, CD34, S100, SMA, vimentin, pan-CK, HHF-35, Ki67, ALK, desmin, HMB-45, SATB2, ERG, EMA and CD99) were employed concurrently for the first time for fibroblastic and myofibroblastic oral spindle cell lesions. The data obtained was tabulated and studied.
UNASSIGNED: NA. Results: Using cytological scoring criteria and panel of immunohistochemical makers, the cases analysed and characterized were desmoplastic fibroma, fibrosarcoma, leiomyosarcoma, nodular fasciitis, neurofibroma and epithelioid inflammatory myofibroblastic sarcoma (EIMS).
UNASSIGNED: The diagnostic strategies need to be upgraded for the diagnosis of spindle cell lesions. Emphasis must be placed on cytomorphology, an immunohistochemistry (IHC) panel of markers is imperative for the accurate diagnosis of fibroblastic and myofibroblastic oral spindle cell lesions.

Mesenchymal breast tumors are a rare and diverse group of tumors that present some of the most challenging cases for multidisciplinary breast cancer teams. As a result of overlapping morphologies and a lack of large-scale studies on these tumors, practices are often heterogeneous and slow to evolve. Herein, we present a non-systematic review that focuses on progress, or lack thereof, in the field of mesenchymal breast tumors. We focus on tumors originating from fibroblastic/myofibroblastic cells and tumors originating from less common cellular origins (smooth muscle, neural tissue, adipose tissue, vascular tissue, etc.).

Fibroblastic rheumatism (FR) is an uncommon disease of the skin, characterized by the presence of non-tender cutaneous nodules accompanied often by other rheumatic manifestations. This condition shows male predominance, no age preference and unpredictable course, resulting frequently in permanent joint damage. A 60-year-old man came to our department with a 4-year history of multiple non-tender nodules and morning stiffness affecting mainly the upper extremities. Clinical examination revealed arthritis of the hands, confirmed by imaging tests. Laboratory exams were unremarkable. A skin nodule biopsy showed a dermal collagenous lesion with myxoid areas composed of spindle and stellate cells. Immunohistochemical staining demonstrated positivity for CD68 and negativity for CD34, S100, EMA and desmine. FR was diagnosed and the patient started methylprednisolone 16 mg/day. Hydroxychloroquine 400 mg/day and methotrexate 15 mg/weekly were further added as steroid-sparing agents with clinical benefit. Clinicians should be aware of this underreported entity, which can rapidly lead to irreversible deformities.

OBJECTIVE: PRRX1-NCOA1-rearranged fibroblastic tumour is a recently described, rare mesenchymal tumour. Only four cases have been previously reported. The aim of this article is to report six additional cases of this unusual mesenchymal neoplasm, with an emphasis on its differential diagnosis.
RESULTS: The six cases were from three females and three males (age, 20-49 years; median, 42 years). Three tumours were located on the abdominal wall; two from the shoulder/axillary areas, and one on the lateral hip. All presented as slow-growing subcutaneous nodules, ranging from 26 to 55 mm (median, 40 mm). The tumours consisted of circumscribed, variably cellular nodules composed of relatively bland plump spindled to epithelioid cells arranged singly, in cords, and occasionally in nests, embedded in hyalinised and collagenous stroma. Small hypocellular myxoid zones with ropey collagen fibres were present, as were irregularly dilated, gaping, crescent-shaped or staghorn-like thin-walled vessels, best appreciated at the periphery. Immunohistochemistry for CD34, S100, MUC4 and STAT6 was consistently negative. RNA-sequencing revealed PRRX1-NCOA1 fusions in all cases. Of the four cases with limited follow-up (1.5-4 months), none recurred following local surgical excision.
CONCLUSIONS: The morphological features of PRRX1-NCOA1-rearranged fibroblastic tumour overlap with those of RB1-deficient soft-tissue tumours, solitary fibrous tumour, and low-grade fibromyxoid sarcoma/sclerosing epithelioid fibrosarcoma. This differential diagnosis can be resolved with a combination of careful morphological study and the application of a panel of immunostains, although molecular genetic study is most definitive. The natural history of PRRX1-NCOA1-rearranged fibroblastic tumour appears to be quite favourable, although longer-term study of a larger number of cases is warranted.

BACKGROUND: Pediatric fibroblastic/myofibroblastic tumors (PFMTs) can be challenging to definitively classify. Large case series or diagnostic updates have not been recently published despite identification of molecular alterations that could improve diagnostic accuracy. Our review of the literature found that over two-thirds of the more than 30 types of PFMTs harbor recurrent molecular alterations. We performed an institutional review of PFMTs to highlight limitations of a predominantly morphological classification, and evaluated the utility of a next-generation sequencing assay to aid diagnosis.
METHODS: PFMTs identified over a period of 12 years were reviewed, categorized per the new WHO classification, and tested using the Oncomine Childhood Cancer Research Assay.
RESULTS: Eighty-seven specimens from 58 patients were reviewed; 50 were chosen for molecular analysis, 16 (32%) lacking definitive classification. We identified alterations, some novel, in 33% of assayed cases. Expected alterations were identified for most known diagnoses and mutations were identified in 6 of 16 tumors (38%) that were initially unclassified.
CONCLUSIONS: We confirmed a significant subset of PFMTs remain difficult to classify using current criteria, and that a combined DNA/RNA assay can identify alterations in many of these cases, improving diagnostic certainty and suggesting a clinical utility for challenging cases.

Gnathic osteosarcoma is a rare malignant mesenchymal neoplasm showing evidence of osteoid matrix formation. Clinical behaviour and radiological appearances overlap with benign osseous lesions and are prone to misdiagnosis. Early diagnosis of osteosarcoma plays a crucial role in the treatment plan and prognosis. Herein a rare case of parosteal osteosarcoma of fibroblastic histologic subtype affecting the angle of the mandible in a 12-year-old female is presented.

Pediatric fibroblastic/myofibroblastic tumors are rare but include a wide variety of benign to malignant tumors. Given their uncommon frequency, they may present as a diagnostic dilemma. This article is focused on using clinical and pathologic clues in conjunction with the increasingly relevant and available molecular techniques to classify, predict prognosis, and/or guide treatment in these tumors.

Myxofibrosarcomas (MFSs) are sarcomas most commonly seen in older patients. These are tumors of deep soft tissue seen in subcutaneous tissue and deep fascia, with frequent muscle involvement. These sarcomas are notorious for recurrences and progression to a higher grade with notable metastatic potential. They are very often under-diagnosed owing to their inherent morphological variability. A case of MFS is presented as a cutaneous, exophytic, polypoidal mass because of its rarity and importance of timely diagnosis, as under-diagnosis may lead to inadequate clearance of tumor, recurrences, metastases and increased mortality.

Despite immune microenvironment of head and neck squamous cell carcinoma (HNSCC) has been studied, there are no sufficient data on the role of tumor stroma factors. The aim of the study was to explore the prognostic and predictive role of these factors in a large series of HNSCC.
This is a retrospective study of 266 patients with laryngeal and pharyngeal SCC. Clinical data were correlated with the following histological parameters: tumor-stroma ratio (TSR), tumor budding activity (BA), cell nests size (CNS), and stroma type.
Stroma-rich tumors, tumor budding, smaller CNS at core and front area, and fibroblastic stroma type, were all adverse prognostic factors (P < 0.0001, 0.001, 0.003, 0.001, 0.007, respectively). Stroma-poor tumors and with larger CNS showed good response to induction chemotherapy (P = 0.009 and 0.02, respectively).
TSR, tumor budding, CNS, and stroma type are important prognostic and predictive factors in laryngeal and pharyngeal SCC.

BACKGROUND: Fibroblastic connective tissue nevi (FCTN) are benign skin conditions characterized by bland spindle cells infiltrating the reticular dermis and the upper subcutis with preservation of adnexal structures. A subset of FCTN expresses CD34, which may cause difficulties in the differential diagnosis, in particular with dermatofibrosarcoma (DFSP). We aim to study clinical and histological main features of congenital FCTN to better understand their heterogeneity.
METHODS: We present 3 cases of congenital FCTN with misleading pseudo-tumoral presentations and compare them with published cases in literature. We provide a diagnostic algorithm for congenital neonatal connective tissue tumors.
RESULTS: Clinically, FCTN mostly present as well-limited and nontender plaques or nodules mainly located in the neck and face areas or in the trunk. Histologically, FCTN are composed of irregularly distributed fascicles of bland spindled cells and are defined by a list of fundamental features: (i) no atypia, pleomorphism, or mitotic activity; (ii) skin appendages entrapped but unaffected; (iii) no evidence for malignancy. In most cases CD34 is positive, but in some cases, cells can express SMA or are even CD34- and SMA-.
CONCLUSIONS: The initial presentation and natural history of FCTN fit better with a neoplasm than with a hamartoma. Thus, we suggest replacing the term \"nevus\" with tumor and considering fibroblastic connective tissue tumor (FCTT) as the right denomination of this clinico-pathological entity. FCTTs are difficult to diagnose due to their clinical heterogeneity. Clinical and histological malignant and benign differential diagnoses are discussed.