Pet/CT or CT scanning for malignancy in dermatomyositis – pro
Dermatomyositis is an autoimmune disease that has a characteristic skin eruptionand may be autoimmune; it is sometimes associated with malignancy. Because this is a rare disease, not much is known about this association and there are no guidelines to my knowledge, but experts often recommend CT scanning to exclude coexistent malignancy. A link between malignancy and DM is well established. Numerous case series and population-based studies have confirmed this association, although estimation of malignancy incidence among DM patients varies from 15% to 27%.
Few studies have investigated specific imaging modalities for DM malignancy screening. A role for screening with CT chest/abdomen/pelvis was shown in a retrospective analysis of 33 DM patients, 13 of which were found to have malignancies (15). However, routine screening failed to identify four malignancies and screening not supported by physical exam (PE) and/or symptoms was positive in only 13% of cases. On the other hand, several recent cohort studies have found that CT scans were the most common test that detected an underlying malignancy when DM patients underwent malignancy screening.
A single prospective study compared whole-body [18F] fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) to “conventional” malignancy screening among DM patients. In this study, conventional screening included CT thorax/abdomen, mammography, gynecological examination, pelvic ultrasound, and tumor marker analysis [CA125, CA19.9, carcinoembryonic antigen, prostate-specific antigen (PSA)]. Nine of 55 patients were diagnosed with malignancy. Notably, FDG-PET/CT and conventional screening had similar overall positive and NPVs for malignancy among DM patients (92.7%).
A recent review concludes that a routine search for underlying malignancy is not justified in dermatomyositis patients. Kanna et al srite: ” We believe one of the most important steps to this, as emphasized by the HVCTF-ACP in their framework, is to identify the subset of DM patients in whom malignancy screening has high value. To optimize the risk: benefit ratio of any screening test, it is well-known that it is important to define a high-risk subgroup. As only a minority will ever develop malignancy (15–27%) identifying the subset of DM patients who warrant malignancy screening appears to be a feasible goal. Additional work to be done includes collecting data to, (I) minimize malignancy overdiagnosis in DM patients, (II) identify the prevalence of false-positive malignancy diagnoses in DM patients, (III) assess patient morbidity/mortality associated with malignancy screening, and (IV) calculate the cost-effectiveness of malignancy screening.
As summarized above, research has already laid the groundwork necessary for more focused projects that may eventually establish high-value malignancy screening guidelines within the setting of DM. For example, although malignancy risk may persist years after DM diagnosis, it has reproducibly been found to be highest within the first 12 months, supporting this is likely the time period that will be associated with an optimal risk: benefit ratio and the highest screening value (10,13). Furthermore, the clinical and laboratory factors that have been shown to predict or protect against underlying malignancy should be more meticulously explored to determine which, if any, can truly be used to further increase/decrease the level of clinical suspicion for underlying malignancies.”
Khanna U, Galimberti F, Li Y, Fernandez AP. Dermatomyositis and malignancy: should all patients with dermatomyositis undergo malignancy screening?. Ann Transl Med. 2021;9(5):432. doi:10.21037/atm-20-5215
Agnès Sparsa, Eric Liozon, François Herrmann, Kim Ly, Valérie Lebrun, Pascale Soria, Véronique Loustaud-Ratti, Marie-Laure Bouyssou-Gauthier, Serge Boulinguez, Christophe Bédane, Marie-Odile Jauberteau, Elisabeth Vidal, and Jean-Marie Bonnetblanc
Routine vs Extensive Malignancy Search for Adult Dermatomyositis and Polymyositis: A Study of 40 Patients
Arch Dermatol, Jul 2002; 138: 885 – 890.
Scheinfeld N. A review of the cutaneous paraneoplastic associations and metastatic presentations of ovarian carcinoma. Clin Exp Dermatol.2008 Jan;33(1):10-5. Epub 2007 Nov 3. (s)