Pleomorphic Liposarcoma: A Series of 120 Cases With Emphasis on Morphologic Variants.

Pleomorphic liposarcoma (PLPS) is a highly aggressive sarcoma comprising variable numbers of pleomorphic lipoblasts mixed with undifferentiated pleomorphic sarcoma (UPS)-like areas. Morphologic variants, such as myxofibrosarcoma-like or epithelioid, may cause diagnostic confusion, especially on a core biopsy, but there are few data on the prognostic significance of these features. A total of 120 PLPS biopsies and resection specimens were reviewed and catalogued based on the presence of myxofibrosarcoma-like, UPS-like, and epithelioid foci, in 10% increments. The clinical parameters were collected. Cases occurred in 75 males and 45 females, ranging from 8 to 98 years (median, 62.5 y). Cases arose in the extremities (n=72), trunk (n=32), head/neck (n=10), bone (n=4), mediastinum (n=1), or viscera (colon polyp, n=1). Of those with known depth (n=81), 40 were intramuscular, 34 were subcutaneous, and 7 arose in the dermis. Their sizes ranged from 1 to 24.5 cm (median, 7 cm). Of the patients with ≥1 month of follow-up (n=70), 5 had recurrence and 15 had metastasis. The 5-year overall survival and event-free survival rates were 66.2% and 63.1%, respectively. Tumors ≥5 cm had inferior overall survival compared with tumors <5 cm. The presence of epithelioid areas was also statistically significant in terms of poorer overall survival and event-free survival, while tumors with ≥50% undifferentiated pleomorphic-like areas had better overall survival. There was a trend towards poorer outcomes in tumors with necrosis (≥1%). PLPS is an aggressive adipocytic malignancy that is most commonly present in the extremities of older adults. The morphologic features of these tumors are diverse, and they may be mistaken for UPS or myxofibrosarcoma, carcinoma, and melanomas, particularly on biopsies. Tumor size, necrosis, and epithelioid morphology are associated with adverse prognosis.

Head and Neck Low-Grade Fibromyxoid Sarcoma: A Clinicopathologic Study of 15 Cases.

Low-grade fibromyxoid sarcoma (LGFMS) is an uncommon mesenchymal tumor usually arising in the lower extremities and trunk. Only rare examples in the head and neck region have been reported. Fifteen cases of head and neck LGFMS were retrieved. MUC4 was performed on all cases. Results for smooth muscle actins, ß-catenin, desmin, S100 protein, Epithelial membrane antigen (EMA) and STAT6 immunohistochemistry, as well as FUS rearrangement status, were recorded when available. Sites included neck (8), supraclavicular region (4) and orbit (1), parapharyngeal space (1) and lower lip (1). The age of the patients ranged from 3 to 97 years (median, 26 years). Tumors displayed classical morphologic features of LGFMS, as described. All cases (15/15) were positive for MUC4, and all cases tested (4/4) harbored FUS rearrangement. Variable positivity for EMA was identified in one case. Follow-up was available in 11 patients, ranging from 2 to 240 months (mean 71.4 months; median, 44 months). Three tumors recurred locally; none metastasized. In conclusion, although distinctly uncommon, LGFMS may arise in the head and neck region and should be distinguished from other more common spindle cell tumors in these locations. The morphologic, immunohistochemical and molecular genetic features of head/neck LGFMS are identical to those occurring elsewhere. The long-term metastatic risk of LGFMS in these locations remains to be fully elucidated.

CD34-negative Solitary Fibrous Tumor: A Clinicopathologic Study of 25 Cases and Comparison With Their CD34-positive Counterparts.

CD34-negative solitary fibrous tumors (SFTs) are rare and have not been comprehensively studied. We retrospectively reviewed all cases of SFT confirmed with STAT6 immunohistochemistry and/or STAT6 gene fusion between 2013 and 2020 and collected pertinent clinicopathologic parameters. Of a total of 244 cases, 25 (10%) lacked CD34 expression by immunohistochemistry. Compared with CD34-positive SFT, CD34-negative SFT are more likely to arise in the head and neck area (32% vs. 24%, P=0.02) and present as metastatic disease (28% vs. 1%, P<0.0001). A significantly higher percentage of CD34-negative SFT exhibit high-grade cytologic atypia (hypercellularity, round cell or anaplastic morphology, nuclear pleomorphism, etc.) (48% vs. 22%, P=0.0073). There are no significant differences in the distributions of age, sex, tumor size, mitotic count, tumor necrosis, or risk stratification between CD34-negative and CD34-positive SFT. In addition, only 56% of CD34-negative SFT display a typical hemangiopericytoma-like vascular pattern. Special histologic features among CD34-negative SFT include prominent alternating hypercellular or fibrous and hypocellular myxoid areas with curvilinear vessels mimicking low-grade fibromyxoid sarcoma, pulmonary edema-like microcystic changes, and prominent amianthoid collagen fibers. In conclusion, compared with their CD34-positive counterparts, CD34-negative SFT is more likely to present as metastatic disease, show high-grade nuclear atypia, and lack the characteristic hemangiopericytoma-like vasculature, posing a unique diagnostic challenge. The use of STAT6 immunohistochemistry and/or molecular studies may be prudent in soft tissue tumors that appear CD34 negative and lack conventional SFT histopathologic characteristics.

CD10 (neprilysin) expression: a potential adjunct in the distinction of hibernoma from morphologic mimics.

Although the morphologic diagnosis of hibernoma is usually straightforward, some hibernomas have atypical morphologic features, mimicking atypical lipomatous tumors/well-differentiated liposarcomas (ALT/WDLs). In addition, the multivacuolated brown fat cells may be mistaken for lipoblasts by pathologists, especially those without significant soft tissue tumor exposure. Thus, we continue to receive in consultation cases of hibernoma sent for MDM2 fluorescence in situ hybridization testing to exclude ALT/WDL. Testing hibernomas for MDM2 amplification, however, adds cost and delays the final diagnosis. Recently, we have noted expression of neprilysin (CD10, CALLA), a zinc-dependent metalloproteinase involved in the inactivation of various peptide hormones, in brown fat cells, and wished to explore the potential utility of this widely available, inexpensive ancillary test in the differential diagnosis of hibernoma. Formalin-fixed, paraffin-embedded tissue sections from well-characterized cases of hibernoma (n = 48), brown fat (n = 21), ALTs/WDLs (n = 17), pleomorphic liposarcomas (PLPSs) (n = 6), lipomas (n = 5), and fat necrosis (n = 5) were immunostained for CD10, using a commercially available antibody and routine laboratory protocols. CD10 expression was evaluated in both adipocytes and in surrounding stromal cells. The hibernomas occurred in 28 men and 20 women, ranging from 11 to 76 years of age and involved the extremities (n = 25), pelvis (n = 7), abdomen/pelvis/retroperitoneum (n = 7), head and neck region (n = 6), back (n = 2), and chest (n = 1). All showed diffuse, strong CD10 expression in multivacuolated brown fat cells and in the majority of adjacent univacuolated fat cells. Brown adipose tissue from various anatomic structures showed an identical pattern of immunoreactivity. In contrast, CD10 expression was present in the adipocytes of only 3 of 17 (18%) ALTs/WDLs and was absent in lipomas and fat necrosis. Lipoblasts expressed CD10 in 3 PLPSs. Expression of CD10 by surrounding fibroblastic stromal cells was more widespread, present in 13 hibernomas, 10 ALTs/WDLs, 1 instance of fat necrosis, 6 PLPSs, and 4 examples of brown fat. We conclude that immunohistochemistry for CD10 may represent a useful, rapid and inexpensive ancillary test in the differential diagnosis of hibernoma from potential morphologic mimics, especially when morphologic features favor hibernoma. CD10 expression in adipocytes, however, should be rigorously distinguished from fibroblastic stromal cell CD10 expression, a nonspecific finding.

"Transforming the Beast to A Beauty"- Fifteen Years into the Making - Case Report of Congenital Neurofibromatosis.

BACKGROUND: In 1882, the German pathologist Friedrich Daniel von Recklinghausen described a series of patients with a combination of cutaneous lesions and tumours of the peripheral and central nervous system. Succeeding this paper, all of the patients with similar symptoms were given the diagnosis "von Recklinghausen disease". In the 20th century, a distinction was made between Neurofibromatosis type 1 (NF1) and Neurofibromatosis type 2 (NF2) with the help of molecular testing. CASE REPORT: We are presenting the results from multiple surgical esthetic and reconstructive surgical procedures performed on a female patient with severe congenital neurofibromatosis during 15 years (2000-2015). The external appearance of our patient was not reflected in the general public's beauty standards. Convinced that she was unusual and unaccepted by the society, she gathered all of the strength and became our patient at 15 years of age. CONCLUSION: Transforming the patient's life in the next fifteen years improved her overall health and her life quality.

Effective Immunotherapy in Bone Marrow Metastatic Melanoma Presenting with Disseminated Intravascular Coagulopathy.

Malignant melanoma is responsible for the majority of skin cancer deaths and is increasing in prevalence. Bone marrow (BM) involvement by melanoma is rare in the absence of widespread visceral disease. Here, we report the case of a 30-year-old female who presented to the hospital with back pain, low-grade fever, and easy bruising. She was found to be bicytopenic and in disseminated intravascular coagulopathy (DIC). Surprisingly, BM biopsy showed extensive involvement by metastatic malignant melanoma in the absence of visceral or brain metastasis. The unique presentation of this case and the challenge of management of a potentially treatable cancer in a critically ill patient are discussed, alongside a review of published cases of metastatic melanoma in the BM and an exploration of currently available treatment options. The excellent response of our patient to combined immune checkpoint inhibitors has yet to be paralleled in the available literature.

Pulmonary nocardiosis in a patient with idiopathic CD4 T-lymphocytopenia.

Idiopathic CD4 T-lymphocytopenia (ICL) is a rare immunodeficiency characterized by low CD4 T-lymphocyte count, which usually manifests with opportunistic infections. Nocardia as an opportunistic pathogen infecting patients with this condition has rarely been reported. Here, we describe the case of a 46-year-old male who presented with lung mass and respiratory and systemic symptoms and was eventually diagnosed with pulmonary nocardiosis. A workup for predisposing immunodeficiencies suggested a picture of ICL. This case illustrates the importance of considering ICL as a possible predisposing condition when an otherwise healthy individual presents with pulmonary nocardiosis.

An uncommon cause of miliary pattern of pulmonary nodules-diffuse pulmonary meningotheliomatosis.

Pulmonary meningothelial-like nodules are benign lesions that are often incidentally detected in surgically resected lung tissue. These nodules are usually asymptomatic and single. Rarely, they present as diffuse micronodules similar to the miliary pattern seen in tuberculosis or metastatic cancer. While diffuse meningothelial-like micronodules are usually benign, it is important to include this condition in the differential diagnosis of patients presenting with diffuse micronodules. We present the case of a 74-year-old asymptomatic female referred to the pulmonary clinic for evaluation of incidentally detected diffuse bilateral pulmonary nodules. A transbronchial biopsy established a diagnosis of diffuse pulmonary meningotheliomatosis, obviating the need for further invasive workup. She remains stable after more than 2 years of follow-up.