Significance of Atypical Small Acinar Proliferation (ASAP) in Prostate needle biopsy

Many time while reporting prostate needle biopsy, we come across features, which are suspicious for malignancy, but hinder a definitive diagnosis of carcinoma, because of concern about over diagnosis. These are the cases, which are labelled as ASAP, -atypical small acinar proliferation.

Diagnostic criteria for ASAP :
For pathologists, 3 questions need to be answered before the diagnosis of cancer in a small lesion:
• Would you be absolutely confident of this biopsy diagnosis if it were followed by a negative radical prostatectomy?
• Would another colleague pathologist agree with the diagnosis of cancer?
• Can you confidently support the diagnosis of adenocarcinoma based solely on this biopsy?

If the answer to any of these questions is “No,” then use of the more conservative diagnosis of ASAP is recommended.

Reasons for the Diagnosis of ASAP are :

  • Small number of acini in the focus of concern.
  • Small focus size, average 0.4 mm in diameter.
  • Loss of focus of concern in deeper levels.
  • Distortion of acini raising concern for atrophy.
  • Lack of convincing features of cancer (insufficient nucleomegaly or nucleolomegaly).
  • Foamy cytoplasm raising concern for foamy gland carcinoma.
  • Conflicting immunohistochemical findings.

Significance of ASAP. -

Prostate cancer is found in up to 60% of repeat biopsies after the diagnosis of ASAP. Thus
ASAP in a biopsy is a significant predictor for concurrent or subsequent cancer. The high predictive value of atypical small acinar proliferation (ASAP) for subsequent adenocarcinoma indicates a need for repeat biopsy.

1. Borboroglu PG, Sur RL, Roberts JL, et al. Repeat biopsy strategy in patients with atypical small acinar proliferation or high grade prostatic intraepithelial neoplasia on initial prostate needle biopsy. J Urol. 2001;166:866–870.
2. Cheville JC, Reznicek MJ, Bostwick DG. The focus of “atypical glands,suspicious for malignancy” in prostatic needle biopsy specimens: incidence,histologic features, and clinical follow-up of cases diagnosed in a community practice. Am J Clin Pathol. 1997;108:633– 640.
3. Iczkowski KA, Bassler TJ, Schwob VS, et al. Diagnosis of “suspicious for malignancy” in prostate biopsies: predictive value for cancer. Urology.1998;51:749 –757; discussion 757–748.
4. Isabelle Meiers, at el. Atypical Small Acinar Proliferation in the prostate :Pathology Case reviews • Volume 13, Number 4, July/August 2008;13: 129–134


Dr.Prashant A.Jani M.D.FRCPC said...

Some more information:

High grade PIN with adjacent small atypical glands (PINATYP)

May be difficult to determine if small glands represent budding / tangentially sectioned glands from high-grade PIN or invasive cancer next to high grade PIN; no reliable differentiating features

Risk of cancer on repeat biopsy was 46%, higher than high grade PIN alone, indicating patients should be rebiopsied.

sandy said...

I have read your earlier post on ASAP many times & it is reassuring. My worry is:
We get only 1-2 cores in a trucut; it is non TRUS-guided. A rpt bx may / may not be helpful. How often does a TURP help in such cases ? As Ca is supposed to be more commonly involving the peripheral region of the prostate, would a TURP help esp. if the pt. has severe obstructive symptoms ? I have posted a query recently on patho-l; you may like to look at it.
Best regards,Sandhya.

Dr.Prashant A.Jani M.D.FRCPC said...

Hello Dr. Sandhya,
Thanks for your comment.

In patients with previously negative biopsies, the diagnostic yield of TURP is low. Therefore, TURP for diagnostic purposes only cannot be recommended. However, in patients with an abnormal DRE and obstructive symptoms, surgery should be preferred over alternative treatment options.

Detection of prostate cancer by TURP or open surgery in patients with previously negative transrectal prostate biopsies
Urology, Volume 62, Issue 5, Pages 883-887

sandy said...

Thank you.

List of all the posts

Interesting Case

Clinical History:

53 years male,History of hypertension and tachycardia,MRI abdomen:-Left adrenal mass:- size 5.8 cm Right renal mass:- size-3.0cm Microscopic examination of the renal mass showed vascular tumor with diffuse sheets of clear cells having Fuhrman grade III nuclei. There was no evidence of necrosis within the tumor. There was no evidence of extraparenchymal invasion.
Gross examination of the left adrenal gland revealed cortically centered, solid and multinodular mass measuring 6.5 x 6.0 x 5.0 cm and weighing 122 grams. The tumor was encapsulated but showed evidence of extraparenchymal penetration. The tumor had golden brown cut surface with areas of hemorrhage and necrosis. The partial nephrectomy showed 3.0cm x 3.0cm x 3.0 cm yellow solid mass which did not invade into the perinephric adipose tissue.
Microscopically, the adrenal mass had predominant diffuse sheets and focal trabecular arrangements. The former pattern was present in about third of tumor. The cells had clear cytoplasm and round to ovoid nuclei with conspicuous nucleoli. Mitotic rate was 9/50 HPF and included atypical forms. Gross necrosis and capsular invasion were documented microscopically. There was no evidence of lymphovascular invasion. Considering the above mentioned features, a Weiss histopathologic score2 of 7/9 was applied.


The differential diagnosis included Renal Cell Carcinoma (RCC) with contralateral adrenal metastasis, Adrenocortical carcinoma (ACC) with contralateral renal metastasis, synchronous RCC and ACC or synchronous RCC and adrenocortical adenoma. A panel of immunohistochemical stains was performed to sort out the diagnosis. Adrenal tumor demonstrated strong Vimentin positivity and is negative for CK7, CK20, E1/AE3, EMA, Synaptophysin and S100.Renal cell carcinoma was positive for CK7, AE1/AE3, EMA (weak) and Vimentin. It was negative for CK20, Synaptophysin and S100. The difference of immunoprofile between the two tumors documented that they originated from two different primaries.

Final Diagnosis:

The diagnosis of synchronous RCC and ACC rather than metastasis influences the prognosis.


The longest disease free interval after removal of contralateral adrenal metastasis was 12.1 years8 and the longest crude survival was 14.3 years. In contrast non metastazing RCC has an excellent prognosis if no metastasis developed.