Radiologic Manifestations of Mycobacterium chimaera Infection After Open Heart Surgery.

PURPOSE: The objective of this study is to identify and detail the radiologic manifestations of surgical site and disseminated Mycobacterium chimaera ( MC) infection. The aim is to facilitate early identification and diagnosis of MC, considering its indolent nature and the challenges involved in clinically and pathologically establishing the diagnosis. PATIENTS AND METHODS: This was a retrospective cohort study reviewing computed tomography (CT), positron emission tomography (PET)/CT, and magnetic resonance imaging examinations in patients over the age of 18 years with a history of open heart surgery and a clinical or pathologic diagnosis of MC. Two radiology residents, a fellowship-trained nuclear medicine radiologist, and a fellowship-trained cardiothoracic radiologist performed consensus reads to determine the imaging findings seen in MC infection. RESULTS: Twenty-five patients were included. Localized, surgical site infection was more common than disseminated disease. Typical CT findings included peristernal soft tissue thickening, sinus tracts often extending to the cutaneous surface, slowly enlarging fluid collections, and sternal osteolysis. PET/CT findings demonstrated hypermetabolic activity in nearly all patients localized to sites of infection. Imaging findings for disseminated infection included hepatosplenomegaly, lymphadenopathy, involvement of the central nervous system, discitis/osteomyelitis, and distant abscesses. CONCLUSIONS: Imaging plays a vital role in suggesting possible surgical sites and disseminated MC infection acquired from open heart surgery. Radiologists must keep a high index of suspicion given the indolent nature and subtle imaging change over time. PET/CT is most useful in diagnosis and helps in differentiating between a sterile postoperative fluid collection or scarring and active MC infection and helps provide a target for debridement.

Relapsed Breast Implant-Associated Anaplastic Large-Cell Lymphoma Presenting as Refractory Fluid Collections With Low Uptake on FDG PET/CT Scan.

ABSTRACT: Breast implant-associated anaplastic large-cell lymphoma is a rare type of non-Hodgkin lymphoma that occurs years after placement of textured surface breast implants. Patients typically present after the development of pain, a palpable mass, or swelling. We present a case of a 45-year-old woman with recurrent breast implant-associated anaplastic large-cell lymphoma presenting as refractory fluid collections, and the unusual finding of low uptake on FDG PET/CT scan despite being confirmed by cytology.

Incidental dedifferentiated mediastinal liposarcoma on F-18-fluciclovine PET/CT.

Fat-containing mediastinal masses, particularly mediastinal liposarcomas, are rare neoplasms that can grow to large sizes before becoming symptomatic and may be incidentally found on radiology examinations. In this case report, a 67-year-old male with a history of prostate cancer status post prostatectomy presented for an F-18-fluciclovine PET/CT for a rising, clinically detectable PSA and indeterminate pelvic lymph nodes seen on multiparametric MRI of the prostate. No local tumor recurrence or metastatic disease from prostate cancer was identified, but the PET/CT demonstrated a mixed soft tissue and fat density prevascular (anterior) mediastinal mass with low-level radiotracer uptake. Following surgical consultation and resection, the final pathology revealed a dedifferentiated mediastinal liposarcoma. The case presented describes the appearance of an uncommon fat-containing mediastinal mass and describes several other fat-containing mediastinal masses that are important for radiologists to recognize in order to formulate accurate differential diagnoses and ensure appropriate further management for patients. Additionally, this case demonstrates that the radiotracer F-18-fluciclovine is not specific for prostate cancer, and its uptake can be seen with other entities such as in this case of sarcomatous malignancy.

Adrenal Histoplasmosis.

An 89-year-old woman presented with seizure and hyponatremia. CT and MRI demonstrated mass-like enlargement of the adrenal glands and multiple pulmonary nodules. PET/CT performed to evaluate for metastatic disease demonstrated intense F-FDG uptake within enlarged adrenal glands. Given mild uptake in the pulmonary nodules, the differential diagnosis for the adrenal uptake included lymphoma, granulomatous infection, and less likely, metastatic lung cancer.

Rare Variant of Intravascular Large B-Cell Lymphoma With Hemophagocytic Syndrome.

Intravascular lymphoma (IVL) is a rare subtype of diffuse large B-cell lymphoma characterized by a clonal proliferation of lymphocytes restricted to the intravascular space. We present the case of a 60-year-old man with hemophagocytic syndrome secondary to IVL. F-FDG PET/CT demonstrated hepatosplenomegaly with marked diffuse hepatic, splenic, and bone marrow hypermetabolism. The case report illustrates the imaging findings of this uncommon variant of IVL.

Pseudolesions Impersonating Osseous Tumor Involvement on Both Contrast Enhanced CT and FDG PET/CT.

A 27-year-old man with stage IV-B Hodgkin's lymphoma status post autologous peripheral stem cell transplant in 2015 with complete response, presented in 2017 with increasing back pain. Restaging contrast enhanced CT demonstrated left brachiocephalic vein occlusion with peripheral nodular high density areas within C7-T2 vertebral bodies with corresponding radiotracer uptake on same day PET/CT. No matching lesion was seen on noncontrast CT. Findings were consistent with pooling of contrast and radiotracer within vertebral venous plexus collaterals at the cervicothoracic junction secondary to brachiocephalic vein occlusion. Repeat PET/CT with contralateral injection of radiotracer and MRI confirmed absence of osseous lymphomatous involvement.

False-Positive Heat-Damaged RBC Scan for Splenosis: Case of Retroperitoneal Extramedullary Hematopoiesis.

Extramedullary hematopoiesis (EMH) is a well-known compensatory response to severe anemia, most commonly due to a chronic hemolytic anemia such as thalassemia or sickle cell disease. We present a case of a 72-year-old man with autoimmune hemolytic anemia refractory to steroids and splenectomy. An incidental retroperitoneal mass on CT was suggestive of ectopic splenic tissue. However, an alternative diagnosis of EMH was considered, given an atypical appearance on heat-damaged Tc-RBC scan, and was confirmed with biopsy. The case report illustrates the imaging characteristics of EMH, widely known to have increased activity on Tc-sulfur colloid scans.

Lhermitte-Duclos Disease in association with Cowden Syndrome.

Cowden syndrome (CS) is a rare genetic disorder with autosomal dominant inheritance, linked to germline mutations in the PTEN tumor suppressor gene on chromosome 10. Cowden syndrome often co-exists with Lhermitte-Duclos disease (LDD), with LDD included as a major criterion in CD diagnosis. This case involves a woman presenting with many of the classic diagnostic criterions and associations of CD, as well as with several comorbidities and unique objective findings.