Diagnosing DILS and Distinguishing It from Other Conditions

Diagnosing Diffuse Infiltrative Lymphocytosis Syndrome (DILS) can be a complex process because its symptoms overlap with several other conditions ^[1][2]. Because it is rare—occurring in roughly 0.28% of people living with HIV—doctors must carefully rule out more common causes of dryness and swelling ^[3].

The Diagnostic Criteria

A diagnosis of DILS is not based on a single, universally accepted test. Instead, historical definitions generally require persistent symptoms and the exclusion of other causes ^[1][4]. A doctor will consider:

1. HIV-Positive Status: The syndrome is specifically linked to the body’s reaction to HIV ^[1].
2. Persistent CD8 Elevation: A blood test called flow cytometry often shows a persistently high absolute CD8+ T-cell count over time ^[1][5].
3. Sicca Symptoms or Parotid Swelling: Persistent dryness of the eyes and mouth, or painless swelling of the glands in the cheeks (parotid glands) on both sides ^[1][2].
4. Tissue Infiltration: Histologic evidence of CD8-predominant infiltration, often from a biopsy ^[1].

Understanding Your Biopsy Report

If your doctor suspects DILS, they may perform a labial salivary gland biopsy. This involves taking a tiny sample of tissue from the inside of your lower lip ^[1][2]. When you read your pathology report, look for these specific terms:

• Focus Score: A “focus” is a cluster of at least 50 lymphocytes within a 4-mm² area. A focus score of ≥ 1 (which corresponds to a Chisholm-Mason grade of 3 or 4) is primarily a standardized measure used in evaluating Sjögren-pattern salivary-gland inflammation ^[1][6]. A positive score is not diagnostic of DILS on its own and must be interpreted with clinical findings.
• CD8+ Predominance: In DILS, there is a tendency for the cells “clogging” the gland to be CD8+ T-cells. In contrast, in typical Sjögren syndrome, the cells are more often CD4+ T-cells ^[1][7].
• Polyclonal vs. Monoclonal: Your report may mention that the cells are polyclonal. If the cells are monoclonal (all identical clones), it raises a red flag for a different condition, like lymphoma ^[1][8]. However, reactive HIV-associated lesions can sometimes show restricted or clonal populations, and a polyclonal result does not exclude lymphoma. An experienced pathologist must interpret the entire specimen.

Differentiating DILS from Other Conditions

DILS is often called a “Sjögren-like” syndrome, but it is evaluated distinctly. These are typical patterns, not absolute rules:

Other conditions your doctor will consider include:

• Hepatitis C (HCV): This virus can also cause dry eyes and mouth. Your doctor will likely run an HCV antibody or RNA test to rule this out ^[1][9].
• Lymphoma: Because DILS involves an overgrowth of white blood cells, it can look like a cancer of the lymph nodes. Doctors evaluate clonality, tissue architecture, and clinical course ^[1][10].
• Benign Lymphoepithelial Cysts: These are fluid-filled sacs in the parotid glands that are common in people with HIV but do not involve the same systemic CD8+ overreaction as DILS ^[11][2].

Extraglandular involvement is investigated when symptoms, examination, laboratory results, or imaging warrant it; tissue confirmation from internal organs is not routinely needed simply to diagnose DILS, and biopsies are reserved for specialist-directed cases where the result would change management ^[1][4].