The Pathology Report: Deciphering the Map

A pathology report is the definitive “map” of what is happening inside your uterus. For a uterine adenomyoma, this report confirms that the growth is biphasic, meaning it contains two distinct parts: the glandular lining (endometrium) and the muscle (myometrium) ^[1]. Understanding the specific language pathologists use can help you navigate your diagnosis and follow-up care.

Key Features of the Pathology Report

When a pathologist looks at a suspected adenomyoma under a microscope, they are looking for a specific “recipe” of tissues:

• Benign Endometrial Glands: These are normal-looking glands from the uterine lining ^[2].
• Endometrial Stroma: The supporting “cushion” of cells that usually surrounds these glands ^[1].
• Prominent Smooth Muscle: Thick bundles of muscle that shouldn’t typically be mixed so intimately with glands ^[2].

“Pushing” vs. “Infiltrative” Growth

Pathologists often describe how the edges of the growth interact with the rest of your uterus.

• Pushing Growth: The adenomyoma grows like an expanding ball, “pushing” against the surrounding muscle. Even if it grows very large or deep, a pushing border generally supports a benign (non-cancerous) process, though it does not by itself exclude carcinoma ^[2].
• Infiltrative Growth: This describes tissue that “leaks” or invades into the surrounding muscle in an irregular, jagged way. This pattern is carefully checked to rule out destructive invasion from cancer (carcinoma), though irregular or infiltrative-appearing glands can also sometimes be seen in benign adenomyosis or other mimics ^[3]. The overall architecture, cytology, stromal response, and clinical specimen must be interpreted together by a gynecologic pathologist.

Atypical Polypoid Adenomyoma (APA)

If your report mentions an Atypical Polypoid Adenomyoma (APA), it means the glands inside the growth look “atypical.” This usually involves glands that are crowded together or have complex shapes ^[4].

• Low Malignant Potential: While “atypical” can be a scary word, APA is considered a lesion of low malignant potential ^[5]. This means it is not cancer, but it has a higher chance of coming back if not fully removed, and it can occasionally be associated with an increased risk of concurrent or future endometrial hyperplasia or cancer ^[6].
• Squamous Morules: You might see this term on an APA report. These are small, harmless balls of specialized cells often found tucked between the atypical glands ^[7].

Specialized Stains (Immunohistochemistry)

To be absolutely sure of a diagnosis, pathologists sometimes use “stains” to highlight specific proteins in the cells as adjuncts. For APA, two such stains are p16 and SATB2 ^[8].

• p16: In APA, the support tissue (stroma) may show a strong, “block-like” staining pattern ^[8].
• SATB2: This is a protein that often shows up in the nuclei (the control center) of the stromal cells in APA ^[7].
• Why they matter: These stains can help distinguish APA from myoinvasive endometrioid carcinoma (a type of cancer that invades the muscle) ^[8]. However, they are not ordered in every case, and their meaning depends on the component stained and the morphology. Neither stain is a standalone rule-in or rule-out test for APA, and they should not be interpreted in isolation ^[5][9].

The Differential Diagnosis: Ruling Out Mimics

The “differential diagnosis” is the list of conditions that can look like an adenomyoma. Your pathologist’s job is to rule these out:

• Adenomyomatous Polyps: Very similar to adenomyomas but usually less “atypical” and found in a polyp shape ^[5].
• Adenosarcoma: A rare tumor that has benign Müllerian glands but a malignant (cancerous) mesenchymal or support tissue component ^[10].
• Endometrioid Carcinoma: The most common form of uterine cancer. Pathologists distinguish this by looking for “destructive invasion” into the muscle ^[3].

Completeness Checklist

A high-quality pathology report should provide your medical team with specific data points. Ensure your report or doctor addresses:

• Specimen Adequacy: Was this a small biopsy, a “D&C” (scraping), or the whole growth (myomectomy)? Small samples can be harder to diagnose ^[5].
• Margins: Did the surgeon get the “whole thing”? Note that “clear margins” cannot always be assessed in a fragmented hysteroscopic resection, and the report should state whether residual disease can be assessed ^[6].
• Presence of Atypia: Is it a “simple” adenomyoma or the “atypical” (APA) version ^[5]?
• Surrounding Tissue: A separate endometrial sample may be needed to evaluate if there is Endometrial Intraepithelial Neoplasia (EIN) or carcinoma elsewhere in the cavity ^[4].