Endocrine Abstracts

Section 1&2: Case history and investigations: We report the case of a 52-year-old man with recurrent immunodeficiency-related Burkitt’s lymphoma. 11 years following remission of his disease he presented with a firm lump in the parotid region. A biopsy showed histopathological evidence of a relapse. An ¹⁸F FDG PET was undertaken to determine the extent of the disease and response to R-DHAX chemotherapy. Areas of high uptake were identified in both sides of the neck (SUVmax R=24.7, L=30.0). These were further characterised by an MRI which revealed mildly T2-hyperintense heterogenous masses at both carotid bifurcations. It was unclear as to whether these masses were malignant lymphoid tissue or represented a new pathology, such as bilateral paragangliomas (PGLS). The patient had no symptoms of catecholamine excess and this was confirmed biochemically. Plasma normetadrenaline 612 pmol/l [<1000], Plasma metadrenaline <180 [<600], 3-MT <75.0 [<180]. Biopsy of these lesions was too high risk given their proximity to the carotid arteries. Therefore the diagnosis of bilateral PGL required confirmation radiologically as biochemical tests were negative and a biopsy was not feasible. When considering the nuclear imaging modality, we needed a test that would be specific for PGL and, as the tumours were bilateral, we had to consider the effect that a potential SDHx mutation would have on the sensitivity of the test (¹²³I-MIBG has high false negatives rates in SDHx mutated PGL). A Ga-68 DOTATATE was undertaken modality and showed intense tracer uptake (SUVmax 101.9 R and 144.7 l) in both neck masses.

Section 3: Results and treatment: The patient had no familial antecedents but given the confirmed radiological diagnosis of bilateral PGL, genetic testing was performed and identified a pathogenic SDHB variant c.379dupA p.(Ile127fs). The patient currently awaits a surgical opinion.

Section 4: Conclusions and points for discussion: An association of SDHB germline mutations with lymphoproliferative disorders has been proposed based on a limited number of case reports and it is intriguing that there is an overlap in the molecular drivers that predispose to both PGL and lymphoproliferative disorders. This is the first report of an SDHB carrier with Burkitt’s lymphoma. A recent study (N=104) has shown Ga⁶⁸ DOTATATE has a sensitivity of 96% for PCC and PPGL. It is increasingly being considered a first line imaging modality for PGL / PCC based on its superior sensitivity to ¹²³I-MIBG and superior specificity to ¹⁸F-FDG PET.