Incidental Identification of Osteoid Osteoma of Skull Bone on 68 Ga-PSMA PET/CT.

ABSTRACT: An osteoid osteoma (OO) is a benign bone neoplasm, characterized by significant nocturnal pain that usually responds to nonsteroidal anti-inflammatory drugs. It occurs most commonly in the lower extremities and vertebrae. Here, we present a case of carcinoma prostate, who was referred to our department for 68 Ga-PSMA PET/CT scan, and we incidentally found out PSMA-avid OO involving frontal bone of skull, which is a rare finding. To the best of our knowledge, this is the second case in which high PSMA uptake is found in the OO, suggesting a possible PSMA expression related to osteoblastic activity.

Isolated Urinary Bladder Metastasis in Renal Cell Carcinoma Detected on 18F-FDG PET/CT Scan.

ABSTRACT: Renal cell carcinoma (RCC) is an aggressive carcinoma with hematogenous spread commonly to lungs, liver, and bones. However, few cases of isolated urinary bladder metastasis have also been reported. Here we report a case of 63-year-old man, a known case of left RCC (clear cell type), post left nephrectomy, who was on regular clinicoradiological follow-up. He presented with complaints of painless hematuria; on further evaluation, 18F-FDG PET/CT revealed few FDG-avid intramural nodular lesions along the walls of urinary bladder. He underwent TURBT, and the tissue was sent for histopathological examination, which was diagnostic of metastatic RCC.

Interdigitating dendritic cell sarcoma of pleura, diagnostic challenges of a rare disease.

Interdigitating dendritic cell sarcoma (IDCS) is an extremely rare subtype of dendritic cell tumour. The solitary lymph node disease is most commonly seen, but may occasionally present extranodally in skin, intestines, soft tissue, liver or spleen. Here we present a case of IDCS in pleura in 53-year-old man, who presented with loss of appetite and chest pain. The initial biopsy was inconclusive. The patient was started on anti-tubercular treatment considering the higher prevalence of the disease in this part of the world. However, the symptoms worsened after 2 months and repeat PET-CT scan revealed extensive FDG avid lesions in the multiple sites in the body. Repeat PET guided biopsy confirmed this rare IDCS neoplasm. Diagnostic challenges of this rare tumour are discussed.

18F-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography in the Evaluation of Anorectal Malignant Melanoma: A Case Series.

Melanomas are the malignancies that can affect any anatomic region where melanocytes exist (such as the epidermis, eyes, nasal cavity, and anus). Anorectal melanoma is a rare mucosal melanocytic malignancy, comprising 0.8% of all anorectal malignancies. Here, we report a case series of three patients of anorectal melanoma and role of positron emission tomography/computed tomography in diagnosis and follow-up to evaluate the local recurrence and distant metastases. Of three patients, two presented with rectal bleeding and one with obstruction. One patient had recurrence after 10 months, other after 24 months, and third remained disease free post surgery till 9 months.

Metastatic Thyroid Cartilage Lesion from Prostatic Adenocarcinoma on 68Ga-Prostate-Specific Membrane Antigen Positron Emission Tomography-Computed Tomography Scan: Case Series.

Prostate cancer usually metastasizes to regional lymph nodes and bone. Laryngeal cartilage metastases are very rare and only few cases have been published so far describing thyroid cartilage metastatic lesions from prostate cancer. Here, we describe 5 cases of carcinoma prostate, 3 staging and 2 follow-up, where 68Ga-prostate-specific membrane antigen positron emission tomography/computed tomography (PET/CT) scan revealed multiple skeletal lesions along with thyroid cartilage metastasis. Initially, laryngeal cartilage metastases remain asymptomatic and in later stages patients present with symptoms. These metastatic lesions to thyroid cartilage are rare entities and can often easily be missed on conventional imaging. PET-CT imaging has overcome this diagnostic problem due to its ability to provide for both anatomical and functional imaging.

Rare thyroid Cartilage Metastases Detected on 18F-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography Scan.

Metastatic lesions to thyroid cartilage are very rare and can be often missed on conventional imaging. Anatomical and functional fused positron emission tomography/computed tomography (PET/CT) imaging has higher sensitivity as compared to conventional CT imaging and can thus identify such atypical sites of metastasis. Here, we present four cases of thyroid cartilage metastases detected on 18fluorodeoxyglucose PET/CT scan from carcinoma lung, breast, stomach and urinary bladder.

Isolated Splenic Tuberculosis Masquerading as Disease Progression of Hodgkin's Lymphoma on Interim18F-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography Scan.

18F-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) scan is the imaging modality of choice in the management of lymphoma. However, 18F-FDG is a nonspecific tracer for tumoral metabolic activity and infective pathology, thus posing a challenge in accurate response assessment. Here, we present a case of Hodgkin's lymphoma, referred for staging PET/CT scan which showed FDG-avid disease in the mediastinum, and on interim 18F-FDG PET/CT in addition to the mediastinal mass lesion, a FDG-avid lesion was also noted in the spleen suggestive of disease progression. The biopsy report of the lesion was tuberculosis, which was masquerading as disease progression on interim 18F-FDG PET/CT.

Xanthogranulomatous cholecystitis mimicking gallbladder cancer on 18F-fluorodeoxyglucose positron emission tomography/computed tomography scan.

The abnormal thickening of the gallbladder (GB) wall can be caused by a malignant condition like gallbladder carcinoma or by benign lesions such as chronic cholecystitis or xanthogranulomatous cholecystitis (XGC). Mural thickening is a common finding between them as fluorodeoxyglucose (FDG) can be taken up by inflammatory cells also. Here, we present a patient with irregular thickening of the GB wall which was suspected to of GB carcinoma since FDG positron emission tomography/computed tomography scan showed increased tracer uptake in the lesion. However, after surgery the histopathological report was suggestive of XGC.

Utility of different positron emission tomography/computed tomography tracers in the evaluation of incidentally detected dual malignancies: An experience from a tertiary care center.

Multiple primary malignancies in a cancer patient are not a rare occurrence. The most common presentation of multiple primary malignancies is dual malignancies. The usefulness of different positron emission tomography (PET)/computed tomography (CT) tracers in the evaluation of dual synchronous primary malignancies is not well documented. Here, we present a case series, where two patients, referred for PET/CT, after being diagnosed with one primary malignancy were found to be having a second primary malignancy, diagnosed incidentally in PET/CT, further validated by PET/CT with another tracer.

Discordant findings of different positron emission tomography/CT tracers in a case of glioblastoma.

18F-2-fluoro-2-deoxy-D-glucose ([18F]-FDG) positron emission tomography (PET) CT has proven useful in the evaluation of high-grade glioma and is also useful as a predictor of the degree of malignancy in newly diagnosed brain tumors. It is commonly accepted that high-grade gliomas are characterized by increased FDG uptake, whereas the low-grade glioma demonstrates reduced or absent FDG uptake. [18F]-FDOPA is an amino acid PET tracer which is a marker of the proliferative activity of brain tumors and demonstrates positive uptake in all grades of brain tumors; however, the degree of tracer uptake is significantly higher in high-grade tumors as compared to low-grade tumors. Here, we discuss a case where both FDG and DOPA PET/CT scans raised suspicion of low-grade glioma; however, the final histopathology report confirmed WHO grade IV Glioblastoma.

18F-Fluorodeoxyglucose Positron Emission Tomography-Computed Tomography in the Evaluation of Unusual Cutaneous Manifestation of Carcinoma Urinary Bladder.

Bladder cancer is one of the most common malignancies of the urinary tract. Cutaneous metastasis of bladder carcinoma is extremely rare with a limited number of cases, resulting mainly from iatrogenic seeding. Here, we present scan findings of cutaneous metastasis in a known case of carcinoma urinary bladder. The 18F FDG PET/CT scan revealed FDG avid nodular thickening of the skin and sub-cutaneous tissue with ulcerations involving anterior pelvic wall, walls of the scrotum and the base of the penis. Histopathology confirmed the diagnosis of cutaneous and subcutaneous metastasis.

Spinal Tuberculosis Mimicking as Prostate Cancer Metastases in Ga-68 Prostate-specific Membrane Antigen Positron-emission Tomography/Computed Tomography.

Prostate-specific membrane antigen (PSMA) is a type II transmembrane glycoprotein which is overexpressed in prostate cancer. However, the widespread use of PSMA positron-emission tomography (PET) scan revealed various nonprostatic PSMA-avid diseases. Here we present a report of a known case of carcinoma prostate, post orchidectomy, radiotherapy, on hormonal therapy with complain of back pain, referred for Ga68 PSMA PET/CT scan. The scan revealed PSMA-avid lesion of contiguous D6 and D7 vertebrae with associated soft-tissue component. The biopsy of the lesion was suggestive of tuberculosis.

99mTc-MDP Bone Scan Findings in Fibrodysplasia Ossificans Progressiva.

Fibrodysplasia ossificans progressiva is a rare debilitating, connective tissue disease characterized by progressive extraosseous ossification with abnormal great toes. Clinical (hallux valgus), radiological, and classical bone scan findings help to reach diagnosis and prevent patient from unnecessary surgical interventions for fibrodysplasia ossificans progressiva lesions and radiotherapy cycles. Here we present a case where a child presented with multiple swellings over the body and hallux valgus, and further bone scan findings helped to reach the diagnosis. The progressive nature of disease is difficult to halt, but early diagnosis can help in the delay of the disease process, by preventing trauma and giving disease-modifying agents.

Herniated Urinary Bladder Detected on 18F-Fluorodeoxyglucose Positron-Emission Tomography/Computed Tomography Scan Imitating as 18F-Fluorodeoxyglucose Avid Lesion.

Inguinal hernia is a common pathology seen in the general population. However, the presence of herniated urinary bladder in the inguinal canal is a rare condition. Most cases are asymptomatic and are detected incidentally either during surgery or on imaging. Here, we present a report, where a patient, diagnosed case of carcinoma esophagus, was referred for staging 18F-fluorodeoxyglucose positron-emission tomography/computed tomography (FDG PET/CT) scan and revealed FDG uptake in the right inguinal canal, other than primary and metastatic lesions and corresponding CT and fused PET/CT images revealed herniated urinary bladder in the inguinal canal.

Semiquantitative Interpretation Criteria for Fluorodeoxyglucose-Positron Emission Tomography/Computed Tomography in Large-Vessel Vasculitis: Pattern Recognition and Correlation with Polymyalgia Rheumatica.

BACKGROUND: Fluorine-18-fluorodeoxyglucose (18F-FDG)-positron emission tomography/computed tomography (PET/CT) is emerging as a useful imaging modality in suspected large-vessel vasculitis (LVV), owing to its ability to accumulate at the sites of inflammation within the arterial walls. However, there remains scope for standardization of reporting criteria to ensure reproducibility. Recently, a semiquantitative scoring system called "total vascular score" (TVS) has been suggested as a method to standardize and harmonize FDG PET/CT evaluation in LVV patients. The purpose of this study was to assess the clinical utility of the proposed semiquantitative grading scale in LVV patients. MATERIALS AND METHODS: Patients presenting with clinical symptoms of vasculitis, who had undergone a baseline FDG-PET/CT were evaluated. 18F-FDG uptake in the major vessels was quantified with standardized uptake values (SUVsmax) using four-point scale by three independent nuclear physicians. TVS was calculated based on the calculation of the vascular uptake values with respect to mediastinal blood pool and liver uptake and the number of vessels involved. RESULTS: A total of 106 PET-positive patients (74 males and 32 females) were evaluated. The most frequently involved vessels were thoracic aorta >abdominal aorta >subclavian arteries with mean SUVmax values of 4.05, 3.12, and 2.70, respectively. Mean TVS was 13.18 ± 3.4 (range 03-19) among 276 involved vessels. TVS showed significant positive correlation with erythrocyte sedimentation rate (r = 0.82; P < 0.005). 18 patients showed periarticular FDG uptake, with shoulder joint being the most commonly involved joint. CONCLUSION: The simplified visual and semiquantitative grading scale for interpretation and reporting classification provides better objectivity in diagnosis, communication with referring clinicians, and planning in patients of LVV.

Gastric Mucosal Hypertrophy Masquerading as Metastasis From Neuroendocrine Tumor of the Pancreas Detected on 68Ga-DOTANOC PET/CT.

A 57-year-old man, on octreotide treatment for metastatic neuroendocrine tumor pancreas, was referred for whole-body Ga-DOTANOC PET/CT scan to evaluate treatment response. PET/CT scan revealed DOTANOC-avid lesion in the head of the pancreas with multiple tracer-avid soft tissue lesions in the liver, bilateral adrenal glands, and periportal lymph nodes. In addition, diffuse intense DOTANOC-avid mural thickening with intraluminal polypoidal mass formation was noted within the stomach causing significant luminal compromise, histopathological examination of which turned out be hypertrophic hypersecretory gastropathy. This case highlights the possibility of overexpression of somatostatin receptors in gastric hypertrophy, which has been little explored in literature.

Follow-up18F-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography in Evaluation of a Torsion of Uterine Fibroid in an Elderly Female.

Fibroids are rare in postmenopausal females. Torsion of pedunculated uterine fibroid is also a very rare occurrence in elderly females. We report a rare case of an 84-year-old multiparous, postmenopausal female, a treated case of non-Hodgkin's lymphoma, presenting with a large abdominal mass. The comparative positron emission tomography/computed tomography scan study of the patient revealed that a new mass in the abdomen and pelvis connected with the left adnexa with a pedicle and previously seen fibroid was not visualized on the present scan, thus raising suspicion of torsion of subserosal fibroid. Histopathology confirmed the diagnosis of fibroid.

Bone Scan and SPECT/CT Scan in SAPHO Syndrome.

Synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome is a rare clinical entity involving musculoskeletal and dermatologic systems. Its main features are prominent inflammatory cutaneous and articular manifestations. Anterior chest wall pain, more commonly at sternoclavicular and sternocostal joints, along with palmoplantar pustulosis and acne can point to this uncommon syndrome. Here, we report a case of a 15-year-old female, who presented with swelling at the anterior chest wall, was referred for the bone scan. Bone scintigraphy and single-photon emission computed tomography (SPECT/CT) detected classical "bull-head" sign, and further physical examination, for skin lesions, confirmed the diagnosis.

Cutaneous Metastasis from Visceral Organs: 18F-Fluorodeoxyglucose Positron Emission Tomography-Computed Tomography Scan Aiding in Localizing Primary Site.

Skin metastases are rare from systemic malignancy, and incidence reported is between 0.7% and 9% in various malignancies and usually occur in advanced stage. Here, we report three cases, one each of carcinoma esophagus, carcinoma breast, and carcinoma lung, where patients presented with metastatic cutaneous lesions and positron-emission tomography-computed tomography (PET-CT) scan whole body helped in localizing the primary site. Whole-body fluorodeoxyglucose PET-CT scan helps in scanning whole body at once and detect occult primary and metastatic sites.

Fibrodysplasia Ossificans Progressiva - A Rare Genetic Disorder and the Role of Technetium-99m Methylene Diphosphonate Bone Scan.

Fibrodysplasia ossificans progressiva is a rare genetic disease believed to occur in approximately 1 in 2 million people worldwide and is characterized by progressive extraosseous ossification over the course of a lifetime in an inevitable and unpredictable episodic manner, with most patients being confined to a wheelchair by the third decade of life and requiring life-long care. The extraosseous calcification involves ligaments, tendons, muscles, and connective tissue leading to severe restriction of movements. Another hallmark of this condition is abnormal great toes. The diagnosis is often made on clinical and radiological examination, but Technetium-99m methylene diphosphonate (Tc-99m MDP) bone scan is usually indicated to determine the extent of the disease. We hereby present a case series comprising of four patients suffering from this debilitating illness who underwent Tc99m MDP bone scan for initial diagnosis and localizing sites of heterotopic ossification.