Dancing megasperm

Clinical History

Two post-vasectomy patients presented with testicular lumps.

Our first patient had a vasectomy 4 years prior to the current presentation of right testicular lump. The second patient was 30 years post vasectomy and presented with a lump in the left testicle. Neither patient reported any testicular pain.

Imaging Findings

Both patients were scanned using linear high frequency ultrasound probe and the scrotal lumps were noted to correspond to focal dilatation of the epididymis. Within these, multiple tiny motile echogenic foci were seen measuring up to 1.5 mm (32 times larger than an average human spermatozoon). These had the morphology of human spermatozoa with an apparent head and tail (Fig. 1). They also appeared to be capable of independent propulsion (Fig. 2 cine loop).

Discussion

Commonly seen changes post vasectomy include enlargement of the epididymis, development of cysts and inhomogeneous echo-pattern.

We report two cases of a rare and benign condition termed ‘dancing megasperm’. The incidence of this has been reported at 0.6%. Result for an on-line search for ‘megasperm’ reveals only one published article [1] where 6 cases have been reported. All of these patients presented with severe testicular or inguinal pain and no testicular mass.

In the previous article, the tubular contents of one of the patients were examined microscopically post orchidectomy. This revealed aggregations of up to 25 spermatozoa and macrophages. These were not thought to be capable of independent propulsion and the reason for their motion seen on ultrasound is not yet established.

In contrast to previously reported cases, our patients presented with painless testicular lumps.

We hypothesise that ‘dancing megasperm’ is a rare benign finding on ultrasound seen in post-vasectomy patients. This is being seen more frequently due to the use of newer high frequency probes which offer much improved resolution than before. Awareness of this condition would be useful as its bizarre sonographic appearance could lead to unwanted investigation or intervention.

Differential Diagnosis List

Final Diagnosis

Dancing megasperm

URL:	https://eurorad.org/case/9465
DOI:	10.1594/EURORAD/CASE.9465
ISSN:	1563-4086