Scientific Papers

Adrenal schwannoma can be FDG-Avid on PET/CT: case report and review of historic institutional pathology | Diagnostic Pathology

A fifty-year-old male patient underwent routine laboratory analysis during an annual primary care visit which was significant for a mild transaminitis. He subsequently underwent an abdominal ultrasound noting hepatic steatosis and an incidental 6 cm left upper quadrant mass. His past medical history is significant for hypertension controlled with combination lisinopril/hydrochlorothiazide, obesity with a BMI of 39, and current smoker. He had no prior surgical history. His family history was significant only for his mother with uterine cancer.

He was subsequently evaluated with an MRI abdomen revealing a 6.8 cm well-circumscribed but heterogeneously enhancing left adrenal mass concerning for pheochromocytoma or adrenocortical carcinoma (Fig. 1).

Fig. 1
figure 1

MRI abdomen with contrast, coronal, labeled

Given the size and indeterminate imaging characteristics of the adrenal mass, he underwent an FDG-PET/CT which showed the mass to be intensely FDG-avid without other areas of non-physiologic uptake (Fig. 2).

Fig. 2
figure 2

FDG-PET/CT, axial CT fused, labeled

His functional workup was significant for normal levels of cortisol, potassium, aldosterone, plasma renin activity, DHEAS, metanephrine and normetanephrine; thus a non-functional tumor. As there is concern for malignancy for a large heterogeneously enhancing and metabolically active tumor, adrenalectomy was recommended.

He underwent hand-assisted laparoscopic left adrenalectomy that was converted to an open procedure due to the large size of the tumor, large spleen, obese body habitus, and bleeding from an accessory renal vein that was controlled. The tumor did not have invasive features and was removed without violation of the tumor or adrenal gland.

Microscopic examination showed a well-circumscribed lesion consisting of bland spindle cells with hypercellular (Antoni A) and loosely organized areas (Antoni B) (Fig. 3). Vessels within the tumor were hyalinized (Figs. 3 and 4). Lymphocytic aggregates were seen around the tumor periphery (Fig. 5). The spindle cells were diffusely positive for S-100 (Fig. 6). No atypia, mitotic figures, or necrosis was identified. The final pathology was signed out as adrenal schwannoma (6.1 cm) with an unremarkable adrenal cortex.

Fig. 3
figure 3

Adrenal schwannoma showing hypercellular Antoni A areas (black arrowhead) and loosely organized Antoni B areas (blue arrowhead), with hyalinized vessels (blue arrow) (hematoxylin-eosin, original magnification X100)

Fig. 4
figure 4

The tumor is composed of monomorphic spindle cells (hematoxylin-eosin, original magnification X100) with the background vasculature showing prominent hyalinization (inset, X200)

Fig. 5
figure 5

The tumor is well-circumscribed with associated lymphoplasmacytic cuffing (red arrows) (hematoxylin-eosin, original magnification X100)

Fig. 6
figure 6

Diffuse nuclear and cytoplasmic staining for S-100 protein (Cell Marque 4C4.9, S-100, original magnification X100)

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