Testicular lipomatosis

Testicular lipomatosis is a rare condition characterized by homogeneously hyperechoic non-shadowing lesions within the testes on ultrasound without flow on color Doppler. It is seen as a component of PTEN (phosphatase and tensin homolog) gene hamartoma tumor syndrome (PHTS) which includes:

• Cowden syndrome (multiple hamartoma syndrome)
• Bannayan–Riley–Ruvalcaba syndrome

Clinical presentation

Mostly seen as incidental findings in patients with PTEN hamartoma tumor syndrome. It may be a cause of subfertility.

Pathology

Multiple foci of adipocytes within the testicular interstitium, with no evidence of intratubular calcification or intratubular germ cell neoplasia. No apparent detrimental effect on spermatogenesis or testicular function has been seen.

Radiographic features

Ultrasound

• homogeneously hyperechoic non-shadowing lesions without color Doppler flow
• multiple foci are seen usually measuring ~1-6 mm in diameter
• no distortion of the tunica albuginea (pathognomonic)

MRI

MRI is confirmatory in such cases as the lesions demonstrate the signal intensity of fat. The lesions are hyperintense on T1-weighted images.

Treatment and prognosis

Usually, no treatment is required. It is not possible to confirm the stability of these lesions on ultrasound as they are too numerous. There is no evidence to suggest that lesions are premaligant.

History and etymology

In 2003, Lindsay et al observed hyperechoic foci in the testes of a patient with Cowden syndrome on ultrasound. These foci were hyperintense on T1-weighted MRI and were labeled as testicular hamartomas.

Woodhouse et al studied 8 patients with Cowden syndrome presenting with subfertility and found hyperechoic foci in the testes of 7 of these patients. Four of these patients were biopsied and diagnosed with testicular lipomatosis. They published their cohort study in 2005.

In 2008, Walker et al reported a case of testicular lipomatosis in a patient with Bannayan–Riley–Ruvalcaba syndrome.

Several cases have been reported thereafter.

Differential diagnosis

• testicular microlithiasis
  • show intratubular calcifications which are smaller and much more hyperechoic
• Leydig cell hyperplasia
  • may be hyper/hypoechoic, may show vascularity
• most other testicular lesions, especially malignancies, are hypoechoic
  • germ cell tumors (multifocal) 
    • show associated hemorrhage, fibrosis, calcification and vascularity on ultrasound, distortion of the tunica albuginea and are asynchronous even if bilateral
  • leukemia, lymphoma
    • appear as hypoechoic lesions of variable sizes with increased vascularity
    • associated involvement of epididymis and spermatic cord is seen in lymphoma
  • granulomatous diseases (TB, sarcoidosis)
    • hypoechoic lesions
  • adrenal rests
    • mostly hypoechoic, seen in patients with congenital adrenal hyperplasia

Practical points

Since the association with Cowden syndrome is now well-established, the radiologist may be the first person to suggest this diagnosis.

See also

• Cowden syndrome
• Bannayan–Riley–Ruvalcaba syndrome
• testicular microlithiasis