Case title: “Massive” anal gland mass

A 9-year-old cross breed male neutered was presented to LVS with kyphotic stance and suspected pelvic pain. On examination temperature was 39.2ºC, heart rate 124 bpm, the right popliteal lymph node was mild enlarged and firm, and a mass in the right anal gland was also found.

A CT of the thorax and abdomen was performed, showing a soft-tissue mass on the right anal gland compatible with a neoplasia (Fig. 1), multiple enlarged medial and internal iliac lymph nodes being compatible with metastatic lymphadenopathy (Fig. 2) and a soft-tissue mass infiltrating the right sublumbar muscle (Fig. 3). The thorax was clear without evidence of metastasis.

FIGURE 1 – A rounded-oval well-defined heterogeneous mass (2.8cm LL x 2.1cm DV) located on the right anal gland with moderate to high contrast enhancement displacing laterally the rectum to the left side is appreciated (green arrowhead).

FIGURE 2 – Medial iliac lymph nodes are severe increased in size (right > left) (blue arrowhead).

FIGURE 3 – The right sublumbar muscle is severely enlarged with an infiltrated soft tissue ill-defined mass (4cm CrCd x 3cm DV) attached to it (pink arrowhead).

FNAs of the mass and US-guided FNAs of abdominal lymph nodes were taken (Fig. 4, 5 & 6), coming back as an anal gland apocrine adenocarcinoma and lymph nodes metastasis.

FIGURE 4 – A hypoechoic lobulated well-defined rounded mass (2.8cm x 2 cm) is appreciated on the right anal gland (yellow arrowhead).

FIGURES 5 & 6 – Hypoechoic severely enlarged medial iliac lymph nodes (1.5-2.5 cm in diameter) are appreciated (red arrowheads).

In cases of suspected anal gland neoplasia, CT scan is the gold standard diagnostic imaging technique to assess the exact size and limits of the mass to design a potential surgical plan. This advanced technique is also used to detect the presence of lung or lymph nodes metastasis, and to assess additional organ involvement. In this case the CT scan revealed all medial and internal iliac lymph nodes, sublumbar lymph nodes, and the right epaxial muscle were infiltrated.

With all the information that CT images were able to provide, it could be assessed that the present case was not suitable for surgery given the invasion and spread of the anal gland apocrine adenocarcinoma. Due to the advanced disease, the prognosis of this patient was guarded.