Lumps in the scrotum - Differential diagnosis

Inguinal hernia, hydrocele, epididymal cyst, testicular tumour, varicocele, sebaceous cyst, tuberculous epididymo-orchitis, gumma of the testis, carcinoma of scrotal skin.

Determining the diagnosis

Inguinal hernia

An indirect inguinal hernia often extends into the scrotum. It usually has a cough impulse (i.e. it expands on coughing) and usually reduces with direct pressure or on lying down. It is not possible to get above the lump.

Hydrocele

A hydrocele is an abnormal quantity of peritoneal fluid between the parietal and visceral layers of the tunica vaginalis, the double layer of peritoneum surrounding the testis and which was the processus vaginalis in the fetus. Normally the processus vaginalis becomes obliterated along its entire length, apart from where it surrounds the testis where a potential space remains between the parietal and visceral layers.

Usually painless, unless the underlying testicular disease is painful. A hydrocele has a smooth surface and it is difficult or impossible to feel the testis which is surrounded by the tense, fluid collection (unless, rarely, the hydrocele is very lax). The superior margin can be palpated (i.e. you can get above the lump). It is possible to transilluminate a hydrocele (i.e. the light from a torch applied on one side can be seen on the other side of the hydrocele).

May be primary (idiopathic) or secondary. Primary hydroceles develop slowly (over the course of years, usually) and there is no precipitating event such as epididymo-orchitis or trauma, and the underlying testis appears normal on ultrasound (no testicular tumour). Secondary hydroceles (infection, tumour, trauma) represent an effusion between the layers of the tunica vaginalis (the visceral and parietal layers), analogous to a pleural or peritoneal effusion. In filariasis (infection with the filarial worm Wuchereria bancrofti), obstruction of the lymphatics of the spermatic cord give rise to the hydrocele.

Epididymal cyst

(Also known as a spermatocele if there are spermatozoa in the contained fluid.) Derived from the collecting tubules of the epididymis and contain clear fluid. They develop slowly (over years), lie within the scrotum (you can get above them), and usually lie above and behind the testis. They are often multiple (multiloculated).

Orchitis

In the absence of involvement of the epididymitis, due to a viral infection e.g. mumps. Often occurs with enlargement of the salivary glands.

Tuberculous epididymo-orchitis

Infection of the epididymis (principally) by TB which has spread from the blood or urinary tract. The absence of pain and tenderness is noticeable. The epididymis is hard and has an irregular surface. The spermatic cord is thickened and the vas deferens also feels hard and irregular (a string of beads).

Testicular tumour (seminoma, teratoma)

A solid mass, arising from within the scrotum which, if very large, may extend up into the spermatic cord. They may present with symptoms which mimic an acute epididymorchitis (i.e. pain and tenderness in the testis and fever). Not infrequently the patient reports a history of minor trauma to the testis in the days or weeks preceding the onset of symptoms. They may have undergone an orcidopexy as a child (fixation of the testis in the scrotum for an undescended testis).

The lump is usually firm or hard, and may have a smooth or irregular surface. Examine for abdominal and supraclavicular lymph nodes.

Gumma of the testis

Rare. Syphilis of the testis resulting in a round, hard, insensitive mass involving the testis (a so-called billiard ball). Difficult to distinguish from a tumour.

Varicocele

Dilatation of the pampiniform plexus the collection of veins surrounding the testis and extending up into the spermatic cord (essentially varicose veins of the testis and spermatic cord). Small, symptomless varicoceles occur in approximately 20% of normal men and are more common on the left side. They may cause a dragging sensation or ache in the scrotum. Said to feel like a bag of worms. The varicocele disappears when the patient lies down.

Sebaceous cyst

Common in scrotal skin. They are fixed to the skin and have a smooth surface.

Carcinoma of scrotal skin

Appears as an ulcer on the scrotal skin, often with a purulent or bloody discharge.