PMC8422420_01
A 52-year-old male patient with a history of perianal fistula previously managed conservatively represents with perianal pain. (a) Unenhanced T2-weighted axial MRI showing a 2 cm well-circumscribed T2 hyperintense mass-like lesion (white arrow) in the left ischioanal fossa with a thin hypointense wall and minimal surrounding spiculation. (b) T2-weighted axial MRI at the level of the lower rectum showing the internal opening (asterisks) of the fistula in ano at 2' o clock position. (c) T2-weighted fat-saturated axial MRI image demonstrating the true high signal of the pseudo mass (white arrow).
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F1
T2 hyperintense ovoid uniformly hyperenhancing focus measuring approximately 2 x 1.5 x 3 cm in the left ischioanal fossa [Figures 1 and 2]. The lesion showed no appreciable fluid component resulting in two main etiological considerations, first, a neoplasm arising from a longstanding perianal fistula and second, a solid inflammatory phlegmon.
The same 52-year-old gentleman at the time of second presentation. (a) Post-contrast T1-weighted MRI in coronal orientation clearly delineating the enhancing left transphincteric fistula tract (black arrow) with uniform mass-like enhancement of the adjacent left ischio anal lesion (white arrow). Post-contrast (b) axial, (c) coronal, and (d) sagittal T1-weighted images confirm near-complete uniform enhancement of the lesion (white arrow).
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F2
T2 hyperintense ovoid uniformly hyperenhancing focus measuring approximately 2 x 1.5 x 3 cm in the left ischioanal fossa [Figures 1 and 2]. The lesion showed no appreciable fluid component resulting in two main etiological considerations, first, a neoplasm arising from a longstanding perianal fistula and second, a solid inflammatory phlegmon.
Our 52-year-old male patient underwent pre-surgical perineal ultrasound guided biopsy: (a) High-frequency B mode ultrasound image using a linear 6-15 Hz transducer showing the lesion on MRI to correspond to a well-circumscribed heterogeneously hypoechoic lesion with echogenic foci within (white arrow). (b) Color Doppler image of the same lesion demonstrating mild surrounding vascularity with no internal vascularity(white arrow). (c) B mode ultrasound confirming the 16 G biopsy needle (white arrow) within the lesion during ultrasound-guided tissue sampling for pre-operative tissue diagnosis.
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F3
An ultrasound-guided biopsy was performed, [Figure 3] in view of possible malignancy, which showed suppurative inflammation and granulation tissue with no evidence of malignancy [Figure 4].
The 52-year-old gentleman then underwent surgical excision of the lesion. (a) Low-power image, H and E, original magnification x4, showing fragments of skin and subcutaneous adipose tissue with a disrupted fistula tract. (b) H and E, original magnification x20, demonstrating the fistulous tract within fibroadipose tissue with marked acute inflammation and fibrosis. (c) High-power image, H and E, original magnification x200, revealing dense acute inflammatory infiltrate forming microabscess as well as granulation tissue with reactive endothelial cells. A degenerated hair follicle is also noted at the center (white arrow).
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F4
An ultrasound-guided biopsy was performed, [Figure 3] in view of possible malignancy, which showed suppurative inflammation and granulation tissue with no evidence of malignancy [Figure 4].