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Summary Background Schwannoma is a benign tumor arising from Schwann cells of the peripheral nerves. It is often asymptomatic and can develop in the retroperitoneum, mediastinum, head and neck region, and upper and lower extremities. Schwannoma of the abdominal wall is extremely rare, but differential diagnosis with malignant neoplasms is important to reduce the risk of undertreatment. Methods A narrative review of abdominal wall schwannoma was performed using PubMed, EMBASE, and Web of Science database and the search terms “schwannoma”, “neurinoma”, “neurilemmoma”, “soft tissue tumors”, “neurogenic tumor”, “rectus abdominis mass”, “abdominal wall”. In addition, the hospital charts were reviewed to report the personal experience. Results Only 9 single case-reports of benign schwannoma of the abdominal wall were found in the English medical literature over the past decade. None of the patients received preoperative biopsy and all were resected with clear margins. In addition to the literature review, we report the case of a 58-year-old man referred for a palpable mass in the left upper abdominal quadrant. Ultrasonography and magnetic resonance imaging revealed a solid and well-encapsulated mass inside the left rectus abdominis muscle. A core biopsy of the lesion provided the diagnosis of cellular schwannoma and this was confirmed by histopathologic examination of the surgical specimen. Conclusions Benign schwannoma of the abdominal wall is extremely rare. Percutaneous core needle biopsy is important for the differential diagnosis with more common and biologically more aggressive malignancies, such as desmoid tumors and sarcomas, and may be relevant for planning the most appropriate management.

Neurofibromas are benign peripheral nerve sheath tumours, which are usually solitary and sporadic. Solitary neurofibromas of the breast are rare. The most common location of a breast neurofibroma is the nipple–areola complex. We report a rare case of a 56-year-old woman with a solitary neurofibroma of the right breast sulcus.

Myxoinflammatory fibroblastic sarcoma (MIFS) is a low-grade sarcoma generally arising in adults. We present a case of MIFS in a 5-year-old boy with a palpable nodule in the subcutaneous tissue of the scalp. We carried out a literature review to evaluate the diagnostic patterns based on histologic and cytologic features and possible pitfalls and misdiagnoses. A systematic search for articles of interest published between 1995 and 2011 was performed in MEDLINE and PubMed using the words “myxoinflammatory fibroblastic sarcoma,” “myxohyaline tumor,” and “inflammatory myxoid tumor.” Histology and cytology have a pivotal role in the differential diagnosis between MIFS and other potential soft-tissue mimics, such as nodular and proliferative fasciitis and inflammatory myofibroblastic tumor. Fine-needle aspiration cytology is a safe and useful tool for the diagnosis of pediatric patients with MIFS and is important for an accurate and precise preoperative workup to optimize subsequent management and treatment.

The diagnosis of malignant rhabdoid tumor (MRT) is straightforward if the typical, large eosinophilic rhabdoid cells are identified. We report on two diagnostically challenging cases of pediatric extra-renal MRTs which, when evaluated at incisional biopsy, were composed exclusively of small- to medium-sized round cells with focal spindling, lacking rhabdoid phenotype. This morphology, along with a polyphenotypic immunoprofile, including the expression of vimentin/CD99/cytokeratins/alpha-smooth muscle actin and vimentin/CD99/S-100 protein in case 1 and case 2, respectively, suggested the possibility of Ewing sarcoma (EWS)/PNET. However, molecular analyses failed to show the presence of the EWS/FLI-1 and EWS/ERG fusion transcripts, indicative of the most common translocations, i.e., t(11;22)(q24;q12) and t(22;21)(q22;q12), occurring in this tumor family. The revision of both cases included an immunohistochemical analysis with a commercially available anti-INI1 protein antibody. Immunohistochemistry, showing the absence of INI1 expression in neoplastic cells, strongly supported the diagnosis of MRT. Ultrastructural studies, performed on formalin-fixed tissues, were consistent with the diagnosis of MRT. This study suggests including anti-INI1 protein antibody in the immunohistochemical panel when evaluating pediatric tumors with ambiguous morphological and immunohistochemical features, particularly from small biopsies. A careful evaluation of clinical, pathological, and molecular findings is the key to a correct diagnostic approach of pediatric tumors.