Schwannomas are nerve sheath tumors comprised entirely of Schwann
cells, which normally produce the insulating myelin sheath that covers
peripheral nerves. They are usually homogeneous tumors, frequently located in
the head, neck, spinal cord, and extremities, but rarely in the
retroperitoneum, representing only 6 % of all retroperitoneal
tumors [1]. In a recently conducted literature review, we
found only two published case reports of a schwannoma of the hepatoduodenal
ligament, both in female patients over the age of 40 [2]
[3]
[4].
We report a case of a 29-year-old man who was referred for a
surgical consultation for evaluation of a pericholedochal cystic mass of
uncertain nature, detected during annual ultrasound surveillance of
asymptomatic vesicular polyps. No abnormalities were detected on clinical
examination and in laboratory investigations. Fine needle aspiration guided by
ultrasound revealed amorphous proteinaceous material with rare histiocytes,
mesothelial cells, and spindle cells arranged in bundles and palisades, with no
nuclear or cytoplasmic atypia, suggestive of spindle cell neoplasia or stromal
tumor. Endoscopic ultrasonography was performed to clarify the nature of the
mass, showing a complex cystic lesion in nature, with solid areas, measuring
45 × 29 mm in the sagittal plane, located in the
subhepatic region, keeping the planes of cleavage with the liver, portal vein,
and hepatic artery ([Fig. 1]). Biopsy of the mass
was not possible due to vessel interposition ([Fig. 2]). Abdominal magnetic resonance imaging (MRI)
showed a heterogeneous mass adjacent to the gallbladder ([Fig. 3]). The patient underwent laparotomy with
removal of a multilocular cystic mass of the hepatoduodenal ligament.
Histopathologic examination revealed a finely capsulated spindle cell neoplasm
with whirling pattern, typical Verocay bodies, demonstrating intense and
universal S100 positivity, diagnostic of a benign schwannoma ([Fig. 4]).
Fig. 1 Heterogeneous mass on
endoscopic ultrasound.
Fig. 2 Vessel interposition,
making mass biopsy unfeasible.
Fig. 3 a, b Magnetic
resonance imaging (MRI; b: coronal plane) showing a
heterogenous mass adjacent to the gallbladder.
Fig. 4 Intense and universal
nuclear positivity with S100, revealing the typical cytological and
architectural aspects of schwannoma.
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