Peripheral nerve sheath tumors encompass a wide spectrum of lesions with different biological behavior, including both benign and malignant neoplasms as well as the recent diagnostic category, i.e., “atypical neurofibromatous neoplasm with uncertain biologic potential” to be used only for NF1 patients. Neurofibromas and schwannomas are benign Schwann-cell-derived peripheral nerve sheath tumors arising as isolated lesions or within the context of classical neurofibromatosis or schwannomatoses. Multiple tumors are a hallmark of neurofibromatosis type 1(NF1) and related forms, NF2-related-schwannomatosis (formerly NF2) or SMARCB1/LZTR1-related schwannomatoses. Perineuriomas are benign, mostly sporadic, peripheral nerve sheath tumors that show morphological, immunohistochemical, and ultrastructural features reminiscent of perineurial differentiation. Hybrid tumors exist, with the most common lesions represented by a variable mixture of neurofibromas, schwannomas, and perineuriomas. Conversely, malignant peripheral nerve sheath tumors are soft tissue sarcomas that may arise from a peripheral nerve or a pre-existing neurofibroma, and in about 50% of cases, these tumors are associated with NF1. The present review emphasizes the main clinicopathologic features of each pathological entity, focusing on the diagnostic clues and unusual morphological variants.

Ductal carcinoma in situ (DCIS) shows overlapping epidemiology with invasive ductal carcinoma of the breast, sharing similar risk factorssuch as age, mammographic density, family history, and hormonal therapy as well as genetic factors such as BRCA1/BRCA2, histotypes, and molecular subtypes such as luminal A and B, HER2 enriched, and basal-type, thus suggesting its potential precursor role. A small percentage of patients with a history of DCIS die without a documented intermediate diagnosis of invasive breast carcinoma (IBC). The increased risk of death is usually associated with ipsilateral recurrence such as IBC. The slightly variable incidence of DCIS in different countries is mainly due to a different diffusion of mammographic screening and variability of the risk factors. The majority of DCIS lesions are not palpable lesions, which can be only radiologically detected because of the association with microcalcifications. Mammography is a highly sensitive diagnostic procedure for detecting DCIS with microcalcifications, while magnetic resonance imaging (MRI) is considered more sensitive to detect DCIS without calcifications and/or multifocal lesions. The aim of the present overview was to focus on the clinical, radiological, and pathological features of DCIS of the breast, with an emphasis on the practical diagnostic approach, predictive prognostic factors, and therapeutic options.