Perianal Cysts Workup

Updated: Aug 17, 2021
  • Author: Ruben Peralta, MD, FACS; Chief Editor: John Geibel, MD, MSc, DSc, AGAF  more...
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Workup

Imaging Studies

Computed tomography (CT) of the pelvis may be useful for showing a cystic mass in the perianal region and for helping to rule out anal cancer or abscess. [15]

Magnetic resonance imaging (MRI) has been used in the evakuation of benign lesions involving the anal canal and perianal spaces. [16]

 

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Procedures

Endoscopy may be recommended to help rule out cancer—specifically, anal or rectal cancer.

The cyst may be drained and the fluid sent for cytologic examination. If a question of malignancy exists, the cyst still may be drained, but some controversy remains as to whether or not this may seed the tract.

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Histologic Findings

Anal duct/gland cysts

Commonly, these are lined with epithelium similar to that of normal anal glands. This includes simple columnar epithelium in the deeper portion of the glands, transitional epithelium in the midportion, and squamous epithelium near the orifices. These cysts may stain strongly positive with diastase periodic acid–Schiff stain due to the mucin contained in the anal glands.

Sacrococcygeal teratomas

Teratomas, including sacrococcygeal teratomas, are classified into the following three histopathologic categories:

  • Mature
  • Immature
  • Malignant

Mature teratomas (also known as benign teratomas) contain obvious epithelium-lined structures, mature cartilage, and striated or smooth muscle. Immature teratomas have areas of primitive mesoderm, endoderm, or ectoderm mixed with more mature elements in a highly cellular stroma with mitotic figures.

Malignant teratomas, in addition to mature and/or embryonic tissues, have frankly malignant tissue of germ cell origin, such as germinoma (ie, seminoma or dysgerminoma) and choriocarcinoma. Tumors containing malignant non ̶ germ cell elements, including adenocarcinoma and squamous cell carcinoma, are referred to as teratoma with malignant transformation.

Epidermoid cysts

Commonly, these are unilocular and spherical, a result of inflammation around a pilosebaceous follicle. Situated within the dermis, epidermoid cysts have a lining that is identical in stratification to epidermis. Occasionally, a hair shaft may be found coiled within the cyst.

Dermoid cysts

Grossly, dermoid cysts have a thick-walled, fibrous sac lined by squamous epithelium in which various skin appendages, including hair follicles and sebaceous and sweat glands, are seen. The sac is filled with caseous debris and occasionally has teeth and hair in it.

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