Large bilateral star-shaped calculi in the seminal vesicles.

SP Namjoshi 
 Department of Radiology, Hillingdon Hospital, Pield Heath road, Uxbridge, UB8 3NN, UK.

Correspondence Address:
S P Namjoshi
Department of Radiology, Hillingdon Hospital, Pield Heath road, Uxbridge, UB8 3NN, UK.

Full Text

Calculi in the seminal vesicles (SV) are extremely rare. A patient having large bilateral star-shaped calculi in the SV is reported.

::   Case history

A 82-year-old man presented with lower abdominal constant pain for 12 hours. He mentioned about frequency of urine. There was no history of haematuria, haematospermia, infertility or dysuria. There was guarding in right iliac region with tenderness in hypogastric and both iliac regions. Rectal examination revealed an enlarged prostate. No fever, palpable mass or other abnormality was observed. Serum creatinine and urea were raised. Blood and urine cultures, prostate specific antigen and serum alkaline phosphatase were normal.

The plain film of the abdomen and pelvis showed large bilateral tooth-like densities with star-shaped appearance. Two small densities were seen on the right side superomedially [Figure:1]. Computed tomographic (CT) scan was performed to exclude a pelvic mass and a remote possibility of a dermoid despite the patient being male. It showed the position of large densities within the seminal vesicles, posterolateral to the urinary bladder (UB) and anterior to the rectum, and marked prostatic enlargement [Figure:2]. Hence the densities were interpreted as SV calculi. The density of both calculi in the core portions measured over 1150 Hounsfield units. On the reconstructed CT scans the large stone on the right side measured 35 X 35 X 50 mm and the one on the left, 30 X 20 X 45 mm. There were 3 more calculi of about 1 cm diameter on the left side on the CT scan. No renal stones, SV cysts or pelvic mass were seen.

::   Discussion

First reported in 1928, SV calculi are extremely rare.[1],[2] They are related to urinary tract obstruction, infection, anomalies, or urinary reflux into the ejaculatory ducts and have been reported in children, and also as recurrent ones.[3],[4],[5],[6],[7],[8],[9] Calcification in the SV is known as a normal variant,[10] and is probably in the glandular and/or muscular portion in the wall of the SV and not in the tubular lumen, hence looking denser towards the margins.

The calculi in the present case appear to be distinctly unusual, abnormal and of uncertain cause. Their stellate appearance may be attributed to the possibility of their formation within lumen of the cul-de-sacs of the upper poles and subsequently enlarging in all directions within the diverticula of the tubes in the SV, which are described anatomically.[11] Previously reported and chemically analysed round, oval or flat calculi may have been formed due to regular concentric depo-sition of layers of calcium carbonates, urates and phosphates on the nidus of epithelial cells and mucoid substance, thus having smooth margins and sometimes lamellated appearance on the plain x-ray.[1],[3],[5],[6] One so-called ‘huge’ SV stone measured only 32 X 28 X 22 mm weighing 15gm.[5] Some stones were found to consist of magnesium ammonium phosphate by infrared rays spectrum analysis and the partially resected SV containing those calculi showed no inflammatory or tuberculous changes histopathologically.[8] Others were brown and composed of serum-like organic substance.[7] Very high density of the SV stones in present patient indicates that the calcium particles may have been deposited densely over many years, though he had no symptoms. In this patient, the absence of renal stones, urinary tract or anorectal anomalies, SV cysts and other urinary problems contrasts with the other patients.[3],[4],[6] All previously reported SV stones were situated medially. Per rectal examination failed to detect the SV stones in the present case as they were situated laterally unlike a previous report.[5] Prostate enlargement was probably the cause of his frequency and abnormal renal function, rather than the SV stones and anomalies being at least partly responsible, unlike other patients.[6] Solitary or multiple calculi in the SV were felt above the prostate and seen in the region of UB in or near the midline on the plain x-ray requiring confirmation by retrograde urethrography or seminal vesiculography.[3],[6] One SV stone despite being up to 5mm in diameter, was correctly diagnosed by transrectal US only as it was echogenic with distal shadowing.[7]

In the present case, the calculi were diagnosed as SV calculi non-invasively. They were located laterally in the position of SV, described in CT scan book.[12] In two children, calculi in similar position on CT were proven to be in the SV during operation.[4],[9] The left calculus may have caused UB impression, probably raising suspicion of mass on the US; but CT established that the UB was normal and there was one large star-shaped stone in each SV. They enlarged so much so as to outgrow normal size of SV. Awareness of their possibility made their CT diagnosis easy and eliminated the need to perform more invasive diagnostic imaging. US and CT also confirmed absence of stones in the UB. Exclusion of pelvic mass and UB stones along with confident diagnosis of SV calculi thus helped the clinicians to avoid performing cystolithotomy wrongly, as happened earlier.[4] When round, oval, teeth-like or star-like calcific densities are seen on the plain x-ray or CT scan in the anatomical position of SV in the male pelvis, SV calculi should be considered.

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