Ricerc@Sapienza

Gastrointestinal stromal tumors (GISTs) are neoplasms arising
from mesenchymal cells localized into the muscularis propria
of the gastrointestinal (GI) tract [1]; 5% of GISTs are extra-GISTs
(EGISTs), as they differently originate from adipose tissue adjacent
to the GI tract (omentum and mesentery) or from the pancreas
[2]. So far, both GISTs and EGISTs have been managed
indistinctively by combining surgery, histopathological distinctive
features, imaging, and molecular analysis. Moreover, despite
the contribution of defined genetic backgrounds whose
influence is acknowledged in this type of tumor (i.e. Carney’s
triad or familiar form of GIST), the pathobiology of both GISTs
and EGISTs is not yet fully understood. We describe an interesting
case of an extensively diffuse EGIST involving only omentum
and mesocolon with multinodular growth and peculiar
histological features, and for which a deeper histopathological/
molecular analysis is reported.
Case presentation
A 74-year-old female with a historical diagnosis of multiple myeloma
was referred for anemia, alvus disorders (diarrhea and
constipation), weight loss (15 kg in 6 months), and palpable
mass of the right flank that had appeared 8 weeks before. On
medication for multiple myeloma since 2016 (melphalan combined
with prednisone and bortezomib9; carfilzomib/lenalidomide/
desametasone6 until complete remission), she also
had type II diabetes, treated with oral medications and open
cholecystectomy in the 1980s. Physical examination revealed
the presence of a large mobile non-painful mass in the right
flank apparently from the right colon, without signs of occlusion
or intestinal bleeding. Blood analysis showed: hemoglobin
7.9 g/dL, white blood cells 2.3103/lL, glycemia 191 mg/dL, and
a low potassium level of 2.8 mEq/L.
We first treated the glycemia by insulin infusion and, second,
we investigated the signs of anemia. By lower GI
Submitted: 14 May 2020; Revised: 20 July 2020; Accepted: 28 July 2020