A 60-year-old man was found to have an incidental pancreatic cystic lesion during
surveillance magnetic resonance imaging (MRI) for a known left renal lesion. Endoscopic
ultrasound (EUS) revealed a cystic lesion (2.6 × 2.0 cm) with a single thick septum
in the pancreatic tail ([Video 1]). Needle-based confocal laser endomicroscopy (nCLE) of this lesion was performed
with an AQ-Flex-19 miniprobe (Cellvizio; Mauna Kea Technologies Inc., Paris, France).
This demonstrated nests of cells surrounded by fibrous septa and vascularity, suggestive
of a cystic pancreatic neuroendocrine tumor (PNET) ([Fig. 1]). A pattern of vacuolization was also observed ([Fig. 2 a]; [Video 1]). Fine needle aspiration (FNA) with immunostaining of the sample obtained confirmed
the diagnosis of a well-differentiated PNET.
Fig. 1 Endoscopic ultrasound with needle-based confocal laser endomicroscopy of a pancreatic
cystic lesion demonstrating dark clusters of cells with surrounding gray stroma (trabeculae).
Fig. 2 The pancreatic cystic lesion seen on: a endoscopic ultrasound needle-based confocal laser endomicroscopy showing a unique
pattern of vacuolization intermixed with dark nests of cells; b hematoxylin and eosin staining of the resected specimen (magnification × 400) showing
intracytoplasmic globules (arrows) within the cords of tumor cells. Salt-and-pepper
type chromatin, characteristic of neuroendocrine neoplasms is also seen.
Video 1 Computed tomography, magnetic resonance, and endoscopic ultrasound imaging of a pancreatic
tail lesion. Needle-based confocal laser endomicroscopy shows the established pattern
of a neuroendocrine tumor with an additional novel pattern that corresponds to the
histopathological appearance of the resected specimen.
The patient underwent distal pancreatectomy and splenectomy. Histopathology of the
surgical specimen showed a well-circumscribed mixed solid–cystic lesion ([Fig. 3 a]); synaptophysin immunostaining was reactive and chromatin demonstrated a salt-and-pepper
pattern, consistent with a well-differentiated PNET ([Fig. 3 b]). Additionally, the tumor cells contained hyaline globules of varying sizes within
the cytoplasm ([Fig. 2 b]). This finding correlated with the vacuolization image pattern seen on nCLE. The
presence of these globules has been described in PNETs and solid pseudopapillary tumors,
with the descriptive appearance of cytoplasmic vacuolization [1]
[2]. A similar pattern has been attributed to the presence of cytoplasmic lipid, which
is more common in cystic NETs [3].
Fig. 3 Appearance of the resected specimen: a on gross examination, showing a pancreatic tail mass consisting of collapsed cystic
areas (asterisks) not in communication with the pancreatic duct (arrow); b on immunostaining with synaptophysin, showing diffuse reactivity of the tumor cells,
supporting the diagnosis of a well-differentiated neuroendocrine tumor. Chromogranin
was also reactive (not shown); Ki67 was 3 % and zero mitoses were seen per 10 high-power
fields, in keeping with a WHO grade 2 neuroendocrine tumor.
Napoleon et al. first described the nCLE criteria of cystic PNETs, which have been
validated in resected ex vivo lesions and by independent external observers [4]. The EUS-nCLE findings so far described in cystic PNETs include a trabecular network
of dark cells with surrounding fibrosis and vascularity [4]
[5]. This case presents a unique recurring feature of vacuolization that correlated
with a comparable histopathological pattern. This spectrum of nCLE image patterns
for cystic NETs can further assist in the differentiation of pancreatic cystic lesions.
Endoscopy_UCTN_Code_CCL_1AF_2AZ
Endoscopy E-Videos is a free access online section, reporting on interesting cases and new techniques
in gastroenterological endoscopy. All papers include a high quality video and all
contributions are freely accessible online.
This section has its own submission website at https://mc.manuscriptcentral.com/e-videos
