Unusual Imaging Features Research Articles

Hepatic Portovenous Gas in a Young Male

Hepatic portal venous gas is diagnosed via computed tomography due to unusual imaging features. Hepatic portal venous gas when linked with pneumatosis intestinalis has a high mortality rate and required urgent intervention. We present a case of a 35 year-old male patient with a 12 hour history of generalised abdominal pain, watery diarrhoea and vomiting. He had a background of gout and alcoholism. He had an unmeasurable blood pressure and sinus tachycardia when he was first seen. The patient was stabilized after undergoing vigorous intravenous fluid resuscitation, and he was then sent for a CT scan. A considerable amount of hepatic portovenous gas was seen on the CT scan, coupled with dilated and diffusely aberrant small and large bowel with mucosal enhancement.

Unusual imaging findings associated with abdominal pediatric germ cell tumors.

Germ cell tumors of childhood are tumors arising from germline cells in gonadal or extragonadal locations. Extragonadal germ cell tumors are characteristically located in the midline, arising intracranially or in the mediastinum, retroperitoneum, or pelvis. These tumors are generally easily diagnosed due to typical sites of origin, characteristic imaging findings, and laboratory markers. However, germ cell tumors can be associated with unusual clinical syndromes or imaging features that can perplex the radiologist. This review will illustrate atypical imaging/clinical manifestations and complications of abdominal germ cell tumors in childhood. These features include unusual primary tumors such as multifocal primaries; local complications such as ovarian torsion or ruptured dermoid; atypical presentations of metastatic disease associated with burned-out primary tumor, growing teratoma syndrome, and gliomatosis peritonei; endocrine manifestations such as precocious puberty and hyperthyroidism; and antibody mediated paraneoplastic syndrome such as anti-N-methyl-D-aspartate-receptor antibody-mediated encephalitis. This review aims to illustrate unusual imaging features associated with the primary tumor, metastatic disease, or distant complications of abdominal germ cell tumors of childhood.

Atypical magnetic resonance imaging findings of a vertebral melanotic melanoma in a dog

AbstractAn 8‐year‐8‐month‐old whippet was investigated by magnetic resonance imaging for acute thoracolumbar discomfort and pelvic limb stiffness, which had progressed to severe ambulatory paraparesis and proprioceptive ataxia of the pelvic limbs in the 24 hours before presentation. An aggressive, extradural T10 vertebral mass‐like lesion was identified, with resultant marked compression of the spinal cord. The lesion was heterogeneously T2‐weighted hyperintense and moderately T1‐weighted hyperintense relative to the adjacent vertebrae and paravertebral musculature. Cytological analysis of the lesion was consistent with a melanotic melanoma, which was confirmed by histopathological analysis and immunohistochemistry. The vertebral column is an uncommon location for either primary or metastatic melanomas in both humans and veterinary species. This lesion was particularly unusual in that its imaging characteristics were not typical for melanotic melanoma. This case report illustrates the unusual anatomical and imaging features of this tumour and outlines the diagnostic considerations pertinent to this case.

Crystal Diseases of the Spine.

Gout, calcium pyrophosphate deposition disease, and apatite calcifications, the three main crystal disorders, may involve the spine. These disorders can be completely asymptomatic or associated with various clinical symptoms, such as acute flares and more chronic manifestations. This article presents the typical and more unusual imaging features encountered in these disorders.

The challenging imaging and histopathologic features of diffusely infiltrating breast cancer

PurposeClinical, imaging and outcome observations indicate that diffusely infiltrating breast cancer, presenting as a large region of architectural distortion on the mammogram and conventionally termed classic infiltrating lobular carcinoma of diffuse type, represents a very unusual breast malignancy. This article aims to draw attention to the complex clinical, imaging, and large format thin and thick section histopathologic features of this malignancy, which challenges our current diagnostic and therapeutic management practices. MethodsProspectively collected data from the randomized controlled trial (1977–85) and from the subsequent, ongoing population-based mammography service screening (1985–2019) with more than four decades of follow up in Dalarna County, Sweden provided the database for investigating this breast cancer subtype. Large format thick (subgross) and thin section histopathologic images of breast cancers diagnosed as “diffusely infiltrating lobular carcinoma of the breast” were correlated with their mammographic tumour features (imaging biomarkers) and the long-term patient outcome. ResultsThis malignancy does not have a distinct tumour mass or focal skin retraction at clinical breast examination; instead, it causes an indistinct “thickening” and eventually shrinks the entire breast. A dominant feature is extensive architectural distortion on the mammograms caused by an excessive amount of cancer-associated connective tissue. Unlike other invasive breast malignancies, this subtype forms concave contours with the surrounding adipose connective tissue, a feature that makes it difficult to detect on mammograms. Women with this diffusely infiltrating breast malignancy have a 60% long-term survival. Its long-term patient outcome is surprisingly poor compared to that expected from its relatively favourable immunohistochemical biomarkers, including a low proliferation index and remains unaffected by adjuvant therapy. ConclusionsThe unusual clinical, histopathologic and imaging features of this diffusely infiltrating breast cancer subtype are consistent with a site of origin quite different from that of other breast cancers. Additionally, the immunohistochemical biomarkers are deceptive and unreliable because they indicate a cancer with favourable prognostic features predictive of a good long-term outcome. The low proliferation index is usually indicative of a breast cancer with a good prognosis, but in this subtype the prognosis is poor. If we are to improve the dismal outcome of this malignancy, it will be necessary to clarify its true site of origin, which will be a prerequisite for gaining a better understanding why current management efforts often fail and why the fatality rate is so unfortunately high. Breast radiologists should be watchful for the development of subtle signs of architectural distortion at mammography. Large format histopathologic technique enables adequate correlation of the imaging and histopathologic findings.

Unusual Imaging Features with Poorly Differentiating Squamous Cell Carcinoma of Lung-A Case Report

Unusual Imaging Features with Poorly Differentiating Squamous Cell Carcinoma of Lung-A Case Report

Atypical posterior fossa dermoid cysts: unusual but predictable imaging features.

Atypical posterior fossa dermoid cysts: unusual but predictable imaging features.

Serial changes in liquid biopsy-derived variant allele frequency predict immune checkpoint inhibitor responsiveness in the pan-cancer setting

ABSTRACT Major immunotherapy challenges include a limited number of predictive biomarkers and the unusual imaging features post-therapy, such as pseudo-progression, which denote immune infiltrate-mediated tumor enlargement. Such phenomena confound clinical decision-making, since the cancer may eventually regress, and the patient should stay on treatment. We prospectively evaluated serial, blood-derived cell-free DNA (cfDNA) (baseline and 2–3 weeks post-immune checkpoint inhibitors [ICIs]) for variant allele frequency (VAF) and blood tumor mutation burden (bTMB) changes (next-generation sequencing) (N = 84 evaluable patients, diverse cancers). Low vs. high cfDNA-derived average adjusted ΔVAF (calculated by a machine-learning model) was an independent predictor of higher clinical benefit rate (stable disease ≥6 months/complete/partial response) (69.2% vs. 22.5%), and longer median progression-free (10.1 vs. 2.25 months) and overall survival (not reached vs. 6.1 months) (all P < .001, multivariate). bTMB changes did not correlate with outcomes. Therefore, early dynamic changes in cfDNA-derived VAF were a powerful predictor of pan-cancer immunotherapy outcomes.

Unusual imaging characteristics of a lumbosacral intervertebral disc extrusion in a dog.

Unusual imaging characteristics of a lumbosacral intervertebral disc extrusion in a dog.

Unusual imaging characteristics of thoracic hydatid disease.

Cystic echinococcosis (hydatid disease) is a zoonotic parasitic disease, caused by ingestion of Echinococcus granulosus eggs, that can result in cyst formation anywhere on the body. Hydatid disease is frequently seen in regions where there is human-animal contact and poor socioeconomic development. The prevalence of the disease ranges from 0 to 79 cases/100,000 population. Hydatid cysts are typically found in the liver and lungs, being less common in other parts of the body. Computed tomography or magnetic resonance imaging is often used in order to clarify the sites affected by a hydatid cyst, such as the cranial and thoracic regions, which also facilitates the surgical evaluation and minimizes complications. Although rare, hydatid cysts in atypical locations can provoke unusual complications, with unpredictable findings and symptoms. This essay discusses the radiological aspects of rare thoracic hydatid cysts.

Accuracy of central neuro-imaging review of DIPG compared with histopathology in the International DIPG Registry.

Diffuse intrinsic pontine glioma (DIPG) remains a clinico-radiologic diagnosis without routine tissue acquisition. Reliable imaging distinction between DIPG and other pontine tumors with potentially more favorable prognoses and treatment considerations is essential. Cases submitted to the International DIPG registry (IDIPGR) with histopathologic and/or radiologic data were analyzed. Central imaging review was performed on diagnostic brain MRIs (if available) by two neuro-radiologists. Imaging features suggestive of alternative diagnoses included nonpontine origin, <50% pontine involvement, focally exophytic morphology, sharply defined margins, and/or marked diffusion restriction throughout. Among 286 patients with pathology from biopsy and/or autopsy, 23 (8%) had histologic diagnoses inconsistent with DIPG, most commonly nondiffuse low-grade gliomas and embryonal tumors. Among 569 patients with centrally-reviewed diagnostic MRIs, 40 (7%) were classified as non-DIPG, alternative diagnosis suspected. The combined analysis included 151 patients with both histopathology and centrally-reviewed MRI. Of 77 patients with imaging classified as characteristic of DIPG, 76 (99%) had histopathologic diagnoses consistent with DIPG (infiltrating grade II-IV gliomas). Of 57 patients classified as likely DIPG with some unusual imaging features, 55 (96%) had histopathologic diagnoses consistent with DIPG. Of 17 patients with imaging features suggestive of an alternative diagnosis, eight (47%) had histopathologic diagnoses inconsistent with DIPG (remaining patients were excluded due to nonpontine tumor origin). Association between central neuro-imaging review impression and histopathology was significant (p < 0.001), and central neuro-imaging impression was prognostic of overall survival. The accuracy and important role of central neuro-imaging review in confirming the diagnosis of DIPG is demonstrated.

Primary renal non-Hodgkin's lymphoma: A narrative review of literature.

Renal involvement by Non-Hodgkin's lymphoma (NHL) is very rare, and involvement of the kidney as the primary site of NHL (PRNHL) is much more uncommon. Gold standard for the diagnosis of PRNHL is histology and imaging modalities although helpful are not specific. Nephrectomy has been mostly recommended for low grade lymphomas, and for high grade PRNHLs, chemotherapy without nephrectomy has been recommended as the treatment of choice. This tumor is aggressive with poor prognosis. This poor prognosis is partly because of delayed diagnosis and partly because of unnecessary surgeries, so it should be kept in mind, especially in bilateral renal tumors with unusual imaging characteristics, to take a tissue biopsy before nephrectomy. In this review, we will discuss all the detailed aspects of clinical, pathologic, and imaging characteristics of 83 cases of PRNHL reported in the last 20 years in the English literature so far. For this purpose, all the published cases of the primary non-Hodgkin's lymphoma of kidney were reviewed via a search in PubMed, Scopus, and Google Scholar, (1999-2019), using the keywords of "Primary renal lymphoma" and "Non-Hodgkin's lymphoma and kidney," "renal Non-Hodgkin's lymphoma," "renal lymphoma," and "lymphoma and kidney." There were 83 cases in the published English literature which were reviewed for this article. There was some missing information in some cases which has been recorded as "not reported."

Subchondral Osteoid Osteoma of a Metatarsal Bone: An Uncommon Variant in an Unusual Location

Osteoid osteoma (OO) is a benign bone-forming lesion leading to classical symptoms in the form of pain that aggravates during the night and is relieved by the treatment with salicylates. It constitutes 10% of benign skeletal neoplasms and is seen most often in males between the age group of 7 and 25 years. We report a rare case of subchondral OO of a metatarsal bone with unusual imaging features. This case illustrates the limitations of various imaging modalities in the diagnosis of bone tumors and the need for biopsy and histopathological analysis in difficult cases.

DIPG-46. NON-DIPG PATIENTS ENROLLED IN THE INTERNATIONAL DIPG REGISTRY: HISTOPATHOLOGIC EVALUATION OF CENTRAL NEURO-IMAGING REVIEW

INTRODUCTIONThe role of diagnostic biopsy in diffuse intrinsic pontine glioma (DIPG) remains in question. Distinguishing radiographically between DIPG and other pontine tumors with more favorable prognosis and different therapy is critically important.METHODSCases submitted to the International DIPG registry with histopathologic data were analyzed. Central imaging review was performed by two neuro-radiologists; all cases with imaging features or histopathology suggestive of alternative diagnoses were re-reviewed. Imaging features suggestive of alternative diagnoses included non-pontine origin, <50% pontine involvement (without typical DIPG pattern on follow-up), focally exophytic morphology, sharply-defined margins, or marked diffusion restriction throughout.RESULTSAmong 297 patients with pathology from biopsy and/or autopsy available, 27 (9%) had histologic diagnoses not consistent with DIPG, commonly embryonal tumors (n=9) and pilocytic astrocytomas (n=11). 163 patients had diagnostic MRI available for central neuroimaging review. Among 81 patients classified as characteristic of DIPG, 80 (99%) had histopathology consistent with DIPG (diffuse midline glioma, H3K27M-mutant, glioblastoma, anaplastic astrocytoma, diffuse astrocytoma). Among 63 patients classified as likely DIPG, but with unusual imaging features, 59 (94%) had histopathology consistent with DIPG. 19 patients had imaging features suggestive of another diagnosis, including 13 with non-pontine tumor origin; the remaining 6 all had histopathology not consistent with DIPG. Association between central imaging review and histopathology was significant (p<0.001).CONCLUSIONSThe important role and accuracy of central neuroimaging review in diagnosing or excluding DIPG is demonstrated. In patients with pontine tumors for which DIPG is felt unlikely radiographically, biopsy may be considered to guide diagnosis and treatment.

NIMG-31. NON-DIPG PATIENTS ENROLLED IN THE INTERNATIONAL DIPG REGISTRY: HISTOPATHOLOGIC EVALUATION OF CENTRAL NEURO-IMAGING REVIEW

Abstract INTRODUCTION The role of diagnostic biopsy in diffuse intrinsic pontine glioma (DIPG) remains in question. Distinguishing radiographically between DIPG and other pontine tumors with more favorable prognosis and different therapy is critically important. METHODS Cases submitted to the International DIPG registry with histopathologic data were analyzed. Central imaging review was performed on diagnostic brain MRI (if available) by two neuro-radiologists; all cases with imaging features or histopathology suggestive of alternative diagnoses were re-reviewed. Imaging features suggestive of alternative diagnoses included non-pontine origin, &amp;lt; 50% pontine involvement (without typical DIPG pattern on follow-up), focally exophytic morphology, sharply-defined margins, or marked diffusion restriction throughout. RESULTS Among 294 patients with pathology from biopsy and/or autopsy available, 27 (9%) had histologic diagnoses not consistent with DIPG, most commonly pilocytic astrocytomas (n=11) and embryonal tumors (n=9). Of these 294 patients with biopsy and/or autopsy pathologic data, 163 also had diagnostic MRI available for central neuroimaging review and radiographic comparison. Among 81 patients classified as characteristic of DIPG, 80 (99%) had histopathology consistent with DIPG (diffuse midline glioma, H3K27M-mutant, glioblastoma, anaplastic astrocytoma, diffuse astrocytoma). Among 63 patients classified as likely DIPG, but with unusual imaging features, 59 (94%) had histopathology consistent with DIPG. Nineteen patients had imaging features suggestive of another diagnosis, including 13 with non-pontine tumor origin; the remaining 6 patients all had histopathology not consistent with DIPG (embryonal tumors [n=3, including 1 with medulloblastoma], pilocytic astrocytoma [n=1], and ganglioglioma [n=1]). Association between central imaging review and histopathology was significant (p &amp;lt; 0.001 by the Freeman-Halton Fischer Exact Probability Test). CONCLUSIONS The important role and accuracy of central neuroimaging review in diagnosing or excluding DIPG is demonstrated. In patients with pontine tumors for which DIPG is felt unlikely radiographically, biopsy may be considered to guide diagnosis, prognosis, and treatment.

Unusual MR Imaging Features in CT Hyperdense Posterior Fossa Dermoids: Report of Two Cases

AbstractDermoids, either intracranial or in the rest of the body, usually have typical imaging findings due to their fat contents as fat density in computed tomography (CT) and T1- and T2-hyperintensity in magnetic resonance imaging (MRI). Variable imaging appearances have been described due to soft tissue contents, hair, calcification, or even tooth. Posterior fossa dermoids have been reported as a specific variant that shows hyperdensity in CT and mixed signal intensity in MRI. We report two cases of posterior fossa CT hyperdense dermoids that showed unusual MRI features in the form of signal loss in magnetization transfer images and lipid peak in magnetic resonance spectroscopy. Both patients underwent surgical resection and histopathological confirmation and the causes of this unusual imaging appearance are discussed.

Mimics of Complications in the Postsurgical Aorta at CT.

Various surgical techniques of the aorta result in expected imaging appearances on CT images that resemble complications such as pseudoaneurysm, perigraft abscess, and dissection. Awareness of these techniques, understanding the clinical situation in which they are performed, and familiarity with the typical appearances and locations of these mimics are essential for accurate interpretation. CT imaging techniques such as electrocardiographic gating and inclusion of a precontrast series can help distinguish an expected postsurgical finding from a complication. Information in the medical record, particularly the operative note, can clarify challenging cases with unusual imaging features. This review article provides examples of expected postsurgical findings at CT mimicking complications. © RSNA, 2019.

NASOPALATINE DUCT CYSTS: A SPECTRUM OF IMAGING PRESENTATIONS

<h3>Background</h3> Nasopalatine duct cysts are the most common nonodontogenic cysts of the oral cavity. These cysts are classified as being developmental in nature because they most likely develop after spontaneous cystic degeneration of the epithelial remnants of the nasopalatine duct. Imaging plays a vital role in the diagnosis and management of these cysts. <h3>Discussion/Conclusions</h3> We present 5 cases consisting of 3 males and 2 females seen in the Oral and Maxillofacial Radiology clinic at University of Toronto Faculty of Dentistry (Toronto, Canada). The ages of the patients ranged from 40 to 65 years. These cases all exhibited unusual imaging features that posed difficulties in interpretation. One potential difficulty in the radiologic interpretation of these entities was that these cysts exhibited a range of growth patterns that were unconventional; for example, some were asymmetric, and their epicenters were not located in the midlines of the anterior maxillae. Furthermore, some entities demonstrated benign-appearing expansile characteristics, whereas others had more aggressive features. Because of their positions and their proximities to the maxillary anterior teeth, the lesions appeared to resorb or displace teeth. Therefore, the possibility that these entities could be interpreted as rarefying osteitis (e.g., radicular cysts) or odontogenic keratocysts could not be ruled out on the basis of plain film imaging alone. Although there is value in planar film imaging as the preliminary imaging modality, atypical features, such as asymmetric location and loss of normal anatomic structures, made routine interpretation difficult. As a result, we undertook advanced imaging of these patients which enabled us to identify additional key features that enabled us to make a more definitive interpretation. This presentation aims to demonstrate the range of atypical presentations of the nasopalatine duct cysts. A clear understanding of this range of imaging features will improve the interpretive skill of oral and maxillofacial radiologists.

Unusual Imaging Findings Associated with Germ Cell Tumors.

Germ cell tumors, because they contain immature and mature elements, can differentiate into different tissue types. They can exhibit unusual imaging features or manifest in a syndromic fashion. The authors describe these features and assign them to one of the following categories: (a) unusual manifestations of metastatic disease (growing teratoma syndrome, choriocarcinoma syndrome, ossified metastases, and gliomatosis peritonei); (b) autoimmune manifestations (sarcoidlike reaction and paraneoplastic syndromes); (c) endocrine syndromes (sex hormone production, struma ovarii, and struma carcinoid); or (d) miscellaneous conditions (ruptured dermoid cyst, squamous cell carcinoma arising from a mature teratoma, Currarino triad, fetus in fetu, pseudo-Meigs syndrome, and pancreatitis). Rare conditions associated with germ cell tumors demonstrate characteristic imaging findings that can help lead to the appropriate diagnosis and management recommendations. When evaluating for potential metastatic disease, alternative benign diagnoses should be considered (eg, growing teratoma syndrome, ossified metastases, ruptured dermoid cyst, gliomatosis peritonei, and sarcoidlike reaction), which may impact management. Germ cell tumors may also lead to life-threatening complications such as extensive hemorrhage from choriocarcinoma metastases or the rupture of mature teratomas, cases in which timely diagnosis is crucial. Autoimmune and endocrine manifestations such as paraneoplastic encephalitis, autoimmune hemolytic anemia, and hyperthyroidism may occur owing to the presence of germ cell tumors and can create a diagnostic dilemma for clinicians. Knowledge of the syndromic and unusual imaging findings associated with germ cell tumors helps guide appropriate management. ©RSNA, 2019.

Paediatric head injury: Usual and unusual imaging features - A retrospective study in a tertiary care hospital

Paediatric head injury: Usual and unusual imaging features - A retrospective study in a tertiary care hospital