Modern neuroimaging methods do not completely rule out false diagnoses of intracranial aneurysms which can lead to an unwarranted operation associated with risks of complications. However, surgical interventions for falsely diagnosed aneurysms are quite rare. The purpose of this study is to demonstrate two clinical cases of false-positive aneurysms and a systematic review of the literature dedicated to the incidence and etiology of false-positive aneurysms, identifying risk factors associated with false-positive aneurysms. A literature search in two databases (PubMed and Web of Science) using keywords \"mimicking an intracranial aneurysm\", \"presenting as an intracranial aneurysm\", \"false positive intracranial aneurysms\", and \"neurosurgery\" was conducted. A total of 243 papers were found in the initial search in two databases. Sixteen papers (including 20 patients) were included in the final analysis. There were 10 women and 10 men. The most common location of false-positive aneurysms was the bifurcation of the middle cerebral artery (MCA). In the posterior circulation, false-positive aneurysms were identified either on the basilar artery, or at the vertebro-basilar junction. The main causes of false intracranial aneurysm diagnosis included artery occlusion with vascular stump formation, infundibular widening, fenestration, arterial dissection, contrast extravasation, and venous varix. In conclusion, summarizing the results of our analysis, we can say that surgical interventions for false-positive aneurysms are an underestimated problem in vascular neurosurgery. Despite extremely rare published clinical observations, the actual frequency of erroneous surgical interventions for false-positive aneurysms is unknown.

Although airway foreign body aspiration (FBA) is a common occurrence in any age group, unrecognized and retained foreign bodies in lungs may result in severe complications, such as lung abscess or bronchiectasis. In rare cases, FBA may present with similar clinical features as many other diseases (e.g. asthma, tumor, pulmonary eosinophilia). Here, we report a rare case of missed FBA in a nine-year-old boy, whose chest CT scan was suggestive of a cavitary lesion in the left lower lobe mimicking congenital pulmonary airway malformation (CPAM). However, surprisingly, flexible bronchoscopy revealed a peanut lodged in the lateral basal segment of left lower lobe, which was subsequently retrieved by a forceps and avoided unnecessary surgical lobectomy. Therefore, FBA can mimic other disorders (e.g. CPAM), and a high index of suspicion and additional diagnostic techniques (e.g. flexible bronchoscopy) may be required to distinguish them. Additionally, FBA should be considered in the differential diagnosis of respiratory disorders in children even lack of aspiration history.

BACKGROUND: Sarcoma may show similarities to malignant melanoma in terms of morphologic and immunohistochemical aspects, making it difficult to differentiate between these two neoplasms during the diagnostic process. This systematic review aims to summarize available evidence on cases of sarcoma that were initially diagnosed as melanoma.
METHODS: A comprehensive search of the MEDLINE/Pubmed, EMBASE, and SCOPUS databases was conducted through March 2023. We included case series and case reports of sarcoma patients that were initially diagnosed as malignant melanoma. PRISMA guidelines were followed.
RESULTS: Twenty-three case reports and four case series with a total of 34 patients were included. The clinical presentation was heterogeneous, and the most involved anatomical regions were lower limbs (24%), head/neck (24%), and upper limbs (21%). IHC positivity was reported for S100 (69%), HMB45 (63%), MelanA (31%), and MiTF (3%). The main reasons for a second assessment were unusual presentation (48%) and uncertain diagnosis (28%). EWSR1 translocation was investigated in 17/34 patients (50%) and found to be positive in 16/17 (94%). The final diagnosis was clear cell sarcoma (50%) or other soft tissue sarcomas (50%).
CONCLUSIONS: Melanoma and some histotypes of sarcoma share many similarities. In cases of atypical lesions, a second diagnosis should be considered, and ESWR1 translocation should be investigated.

Peritoneal histoplasmosis is a rare entity with few cases reported in the literature. We present a case of isolated acute peritoneal histoplasmosis that mimicked an advanced ovarian malignancy in a patient undergoing antitumor necrosis factor therapy for rheumatoid arthritis. We also reviewed the literature on Histoplasma peritonitis.

Synovial osteochondromatosis is an extremely rare benign condition in children and adolescents that have joint pain as a presenting manifestation. It is usually monoarticular with the knee as the most common affected joint. In this article, we describe the case of a female adolescent suffering from debilitating chronic right knee pain initially mimicking juvenile idiopathic arthritis, who was subsequently diagnosed with primary synovial osteochondromatosis. We present a review of synovial osteochondromatosis focusing on the clinical manifestations, radiographic features, histopathologic findings, and treatment, with a summarized review of pediatric patients with initial musculoskeletal presentations who were ultimately diagnosed as synovial osteochondromatosis. Although synovial osteochondromatosis is rare in children and adolescents, this condition should be included in the differential diagnosis of joint pain and may mimic juvenile idiopathic arthritis. Appropriate diagnostic radiography, including both plain radiography and magnetic resonance imaging, is necessary to accurately diagnose this condition. We also emphasize the importance of a multidisciplinary team approach to managing patients with synovial osteochondromatosis.

Introduction Despite tuberculosis being rampant in the Indian subcontinent, most cases of osteoarticular (OA) tuberculosis (TB) are missed until significant bony destruction has occurred. Initial presentation of extra-pulmonary TB mimics many other disease entities while many diseases mimic TB. This may lead to an incorrect diagnosis and sometimes creates a dilemma in reaching the correct diagnosis. The aim of this study was to evaluate a series of pediatric cases of osteoarticular TB, which posed a diagnostic challenge to us. Material and methods Retrospective analysis of case records of pediatric OA-TB patients who had presented to two tertiary level centers of urban India between February 2016 and December 2020 was done. There were a total of 69 patients.  Observations There were 37 males and 32 females. The age range was from two to 17 years. Forty-four patients showed evidence of disease within the spine (dorsal region followed by lumbar, followed by the cervical spine), 16 showed disease of the extremities, six had disease of the girdle bones, and three showed disease of the short bones of hands or foot. In our series, patients presented to us between 15 days to six months from the onset of symptoms. From our series, six cases with atypical clinical pictures have been selected for presentation purposes. In all six cases, the initial presentation was not that of OA-TB. However, with a high degree of suspicion, differential diagnosis of TB was kept in mind, and the diagnosis was confirmed microbiologically. Conclusion A high degree of suspicion is required to avoid missing the diagnosis of osteoarticular TB. Non-invasive advanced radiological investigations such as MRI and microbiological analysis of biopsy specimens aid in arriving at the correct diagnosis.

Silicosis is caused by inhalation of silica dust and is the most common type of pneumoconiosis. The characteristics of silicosis are inflammation of lung tissue and calcified lymphadenopathy of pulmonary hilum, mediastinum and paratrachea. We present a papillary thyroid carcinoma (PTC) case with paratracheal and superior mediastinal calcified lymphadenopathy caused by silicosis. The patient did not exhibit any respiratory symptoms or abnormal chest x-ray findings due to early phase silicosis. The lymph nodes were thought to be metastasis of PTC before surgery. Patient underwent total thyroidectomy with neck and superior mediastinum dissection. Post-surgery pathological examination exhibited coexistence of silica nodules and micrometastasis of PTC in paratracheal lymph nodes, but only silica nodules were observed in superior mediastinum lymph nodes. Patient\'s occupation was office worker but had worked as a stonemason for several decades prior. This is a first observed case of superior mediastinal lymphadenopathy by silicosis mimicking metastasis of PTC. Benign calcified lymphadenopathy may mimic metastasis of PTC in the evaluation of neck or mediastinal lesions.

We report a case of a 75-year-old patient with hypopituitarism, bitemporal visual field deficits and a parasellar mass on pituitary MRI. During surgery, suspicion was raised that a non-functioning pituitary adenoma was accompanied by an abutting diaphragm sellae meningioma, which was confirmed at pathological examination. In retrospect, the initial MRI suggested two separate tumours on the basis of differing densities but this distinction was not seen on the last preoperative MRI.

Occurrences of metastatic prostate cancer imitating a subdural hematoma are limited to a small number of case reports, even though prostate cancer spreads to the dura more than other types of cancer. Here, we present the case of a 64 year-old male whose prostate carcinoma\'s metastasis mimicked a subdural hematoma, and he suffered a middle cerebral artery stroke. Prostate cancer\'s high rate of progression to the dura is disproportionate to its relatively low rate of brain metastasis. Furthermore, we explore the potential molecular implications of prostate cancer\'s propensity to spread to the dura.

BACKGROUND: Sclerosing angiomatoid nodular transformation is a benign disorder of splenic tissue and is often mistaken as a potentially malignant entity in the diagnostic process. To the best of our knowledge, this is the first report of sclerosing angiomatoid nodular transformation mimicking metastasis of melanoma in the literature.
METHODS: A 43-year-old white man presented with a newly found splenic mass 4 years ago to our Department of Gastroenterology. He was diagnosed as having a superficial spreading malignant melanoma localized at his left instep 7 years ago and was successfully treated with radical local resection. Several diagnostic procedures were conducted. Ultrasound showed a hypoechoic lesion in the inferior pole of his spleen with a diameter of 2 cm, blurred boundaries, and inhomogeneous interior pattern. Contrast-enhanced ultrasound was inconclusive and showed only discrete contrast enhancement of the lesion with accentuated nodule-like enrichment of the boundaries in the arterial phase. Computed tomography and magnetic resonance imaging scans showed two splenic lesions which were highly suspicious of metastasis. Magnetic resonance imaging of his head was inconspicuous. Bone scintigraphy showed no abnormal results. Fine-needle aspiration indicated metastasis of the above-mentioned malignant melanoma. We conducted a laparoscopic splenectomy. His intraoperative and postoperative course were uneventful. In contrast to the result of the fine-needle aspiration, the presence of metastasis of melanoma could not be confirmed. Histological analysis revealed nodule-like arrangement of fibroblasts with low cell density and a predominance of dilated capillaries, indicating sclerosing angiomatoid nodular transformation of the spleen.
CONCLUSIONS: There are no preoperative diagnostic imaging procedures which can definitely differentiate sclerosing angiomatoid nodular transformation from malignancies in cases of morphological and immunophenotypic variations of the specimen. Morphological and immunophenotypic variations of the specimen represent a diagnostic challenge and can mimic malignoma. As reported in our case, the specimen obtained by ultrasound-guided fine-needle aspiration led to the diagnosis of metastasis of melanoma. Splenectomy is often conducted due to a splenic mass suspicious of malignoma as described in our case or with unknown valency in different diagnostic imaging procedures.