Prostatic atrophy is characterized by reduced cytoplasm prostatic acinar cells and constitutes a benign mimic of prostate cancer not only on imaging but also histologically.
Terminology
The term 'proliferative inflammatory atrophy (PIA)' is used if it is associated with inflammation.
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Epidemiology
Prostatic atrophy is very common and can be seen in the majority of elderly men 1,2 and has been reported in up to 85% of autopsy specimens 1.
Associations
Prostatic atrophy has been associated with prostatic inflammation 1. There are theories about a potential role in prostatic carcinogenesis but this is still unclear 1.
Diagnosis
The diagnosis of prostatic atrophy is based on typical pathological more specifically histological features.
Clinical presentation
Extensive focal prostatic atrophy can be present with an elevated prostate-specific antigen (PSA) level 2.
Pathology
Prostatic atrophy is characterized by the microscopical appearance of small and crowded glands, which suggest a slow proliferation rate in contrast to the fact that proliferation indices are actually higher than that of normal benign glands 1.
Etiology
Causes of prostatic atrophy include 2:
- prostatic inflammation
- chronic ischemia
- radiation
- androgen deprivation therapy
Subtypes
Prostatic atrophy can be subdivided into the following subtypes 1,2:
- simple atrophy
- partial or focal atrophy
- sclerotic atrophy with cyst formation
- post-atrophic hyperplasia
Microscopic appearance
Microscopically prostatic atrophy is characterized by the following histological features 2:
- crowded glands with little stroma in between
- scant basophilic cytoplasm
- crowded nuclei and prominent nucleoli
Immunophenotype
Immunohistochemistry stains might be positive for p63 or cytokeratin 34βE12.
Radiographic features
Ultrasound
On transrectal ultrasound prostatic atrophy might appear hypoechoic similar to prostate cancer.
MRI
On prostate MRI prostatic atrophy usually appears as wedge-shaped or geographic areas of low signal intensity on T2w images with mildly low ADC values or mild diffusion restriction and/or enhancement often accompanied with volume loss or contour retraction 2,3.
Signal characteristics
- T1: isointense
- T2: hypointense usually wedge-shaped or geographic
- DWI: mild diffusion restriction
- DCE (Gd): moderate enhancement
Radiology report
The radiological report should include a likelihood score, e.g. PI-RADS. If suspicious lesions are found, they should include a description of the following 3:
- form, location and size
- prostatic margins, including retracting contours
- associated findings of the prostate
Differential diagnosis
Prostatic atrophy may mimic prostate adenocarcinoma not only on imaging but also on histology especially the atrophic subtype 1-3.
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