Abstract
BackgroundMost sporadic gastrointestinal stromal tumors (GISTs) occur as solitary tumors, while multiple sporadic GISTs are extremely rare and often misdiagnosed as metastatic GISTs, leading to inappropriate treatment. This study aimed to investigate the clinicopathological characteristics, diagnostic clues, and prognoses of multiple sporadic GISTs.MethodsTwenty-seven patients with multiple sporadic GISTs and 11 patients with metastatic GISTs mimicking sporadic GISTs were analyzed. The clinicopathological characteristics, genetic mutation types, and prognoses were summarized. In addition, 1066 cases of primary GISTs with a single lesion diagnosed at the same hospital were included as controls.ResultsCompared with 1066 cases of primary GIST with a single lesion, multiple sporadic GISTs occurred at an older age, were more common in women than in men, and were located mainly in the stomach. They were generally small in size, had a low mitotic index and were more often rated as very low risk/low risk. Mutation analysis of all available lesions revealed different KIT/PDGFRA mutation patterns among tumors from the same patients. No patient relapsed during the follow-up period. Among 11 patients with metastatic GISTs that mimicked multiple sporadic GISTs, multiple lesions from the same patient always had concordant pathological and mutational characteristics; namely, they carried an identical KIT/PDGFRA mutation, and the mitotic index was usually high.ConclusionsThe prognoses of patients with multiple sporadic GISTs were not worse than those of patients with a single lesion of the same risk under the same treatment. When it was difficult to distinguish multiple sporadic GISTs from metastatic GISTs, multiple lesions in the same patient carried different KIT/PDGFRA mutation patterns, which supported tumor multiplicity, while the concordant hypermitotic phase in multiple lesions of GISTs suggested that the tumor was metastatic.
Highlights
Most sporadic gastrointestinal stromal tumors (GISTs) occur as solitary tumors, while multiple sporadic Gastrointestinal stromal tumors (GIST) are extremely rare and often misdiagnosed as metastatic GISTs, leading to inappropriate treatment
Incidence of multiple sporadic GISTs After excluding familial GISTs (n = 1), syndromic GISTs (n = 3, all with NF-1), SDH-deficient GISTs (n = 2), and metastatic GISTs that mimicked multiple GISTs (n = 11), 27 cases were identified as multiple sporadic GISTs, representing 1.63% of 1660 consecutive surgically resected GISTs in our hospital
Compared with primary GISTs with only one lesion diagnosed at our center between January 2006 and December 2018 (Table 3), multiple sporadic GISTs occurred at an older age, were more common in women than in men, and were located mainly in the stomach
Summary
Most sporadic gastrointestinal stromal tumors (GISTs) occur as solitary tumors, while multiple sporadic GISTs are extremely rare and often misdiagnosed as metastatic GISTs, leading to inappropriate treatment. Familial GISTs (patients with germline KIT or PDGFRA mutations) and special subtypes of GISTs (for example, neurofibromatosis type 1 (NF1)-related GISTs, sporadic succinate dehydrogenase (SDH)-deficient GISTs, and Carney triad syndromerelated GISTs) usually develop as multiple lesions [4,5,6,7]. Sometimes it is difficult to distinguish multiple sporadic GISTs from metastatic GISTs. The clinical management of these patients is not mentioned in current guidelines since reports of the clinicopathological features and prognostic information of multiple sporadic GISTs are still very limited [8,9,10,11,12,13,14]
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