Spontaneous Regression of Primary Cutaneous Diffuse Large B-Cell Lymphoma on Sequential FDG PET.

ABSTRACT: Primary cutaneous diffuse large B-cell lymphoma, leg type is a rare, aggressive lymphoma characterized by skin involvement predominantly in the lower extremities. We present a case of an elderly woman with pathology diagnosis of primary cutaneous diffuse large B-cell lymphoma, leg type with spontaneous regression without systematic therapy documented by sequential FDG PET scans and clinical follow-up.

Differentiating primary from secondary lung cancer with FDG PET/CT and extra-pulmonary tumor grade.

OBJECTIVE: Assess feasibility of differentiating primary from secondary lung cancer in patients with a solid solitary malignant pulmonary lesion (SMPL) and a previously resected extrapulmonary tumor. METHODS: Patients with pathology proven primary or secondary lung cancer from a solitary pulmonary lesion and known histopathology of extrapulmonary tumor were included. Patients with a small pulmonary lesion size, multiple malignant pulmonary nodules or an active infectious/inflammatory process were excluded. Extrapulmonary tumor grade was categorized as low, intermediate and high and was matched to FDG uptake intensity of SMPL, with FDG uptake range (SMPL/Liver SUVmax) of <0.9 for low, 0.91-1.99 for intermediate and >2.0 for high extrapulmonary tumor grade. RESULTS: Of 274 patients, 62 met the study criteria. 46 are primary and 16 are secondary lung cancer. There are 19 low, 27 intermediate and 16 high grade extrapulmonary tumors. Mean SMPL SUVmax is 8.2 ± 4.5 and SMPL/liver SUVmax is 2.4 ± 1.4. There are 37 cases (60%) with mismatched results (e.g., low FDG SMPL with intermediate or high grade extrapulmonary tumor or vice versa) and 25 matched cases (40%) that are inconclusive (e.g., low FDG with low tumor grade or high FDG with high tumor grade). Of the mismatched cases, we correctly predicted 30 cases (81%) as primary lung cancers. CONCLUSION: A mismatch between the SMPL SUVmax and the extrapulmonary tumor grade could be used to differentiate a primary lung cancer from a metastasis with reasonable accuracy. Our preliminary results support the hypothesis that FDG uptake intensity of a metastatic pulmonary lesion mirrors the tumor aggressiveness of its extrapulmonary neoplasm of origin.

Presence of Macrotroponin for Over 2 Years in a Young Woman.

We present the case of a 28-year-old woman who presented with nonspecific symptoms with a high-sensitivity troponin I level > 10,000 ng/L, which led to extensive investigations and a hospital stay. Follow-up testing using an alternate troponin assay yielded undetectable levels. Two years later, the patient had a high-sensitivity troponin I level > 1500 ng/L, with experiments confirming the presence of a macrocomplex. We advocate for communication with laboratory professionals to expedite identification of macrotroponin complexes, so that patients and clinicians can reduce the number of unwarranted investigations. Novel teaching points include the importance of identifying macrocomplexes as a source of persistent false elevations and ensuring that a process is instituted to investigate troponin-level elevations when false-positive results are suspected.

Nous décrivons le cas d'une femme de 28 ans qui présentait des symptômes non spécifiques et un taux de troponine I mesuré par dosage ultrasensible s'élevant à plus de 10 000 ng/l, ce qui a mené à des investigations poussées et à une hospitalisation. Lors d'analyses de suivi avec une mesure alternative de la troponine, les taux étaient indétectables. Deux ans plus tard, le taux de troponine I mesuré par dosage ultrasensible était supérieur à 1500 ng/l chez cette patiente, et des analyses ont confirmé la présence d'un macrocomplexe. Nous préconisons une communication avec les professionnels de laboratoire pour accélérer la détection de complexes de macrotroponine, afin de permettre aux cliniciens de diminuer le nombre d'investigations qui ne sont pas nécessaires chez les patients. Les points d'enseignements les plus récents insistent sur l'importance de détecter les macrocomplexes qui pourraient être à l'origine des taux de troponine faussement élevés persistants et de s'assurer qu'un processus soit mis en place pour investiguer les élévations du taux de troponine lorsque des résultats faussement positifs sont suspectés.