Case of a Young Adult with B Symptoms, Lymphadenopathy, and a Strikingly Abnormal RDW

Case at a Glance

A 28-year-old male with a significant family history of lymphoma presented with a four-month history of constitutional symptoms including night sweats, fatigue, and lymphadenopathy. An initial FNA biopsy was inconclusive. Subsequent bloodwork revealed a dramatic and acute increase in Red Cell Distribution Width (RDW) to 39.4%, raising concerns for either a significant underlying pathology or a laboratory artifact.

Patient's Story

A 28-year-old male presented for evaluation of persistent symptoms over the preceding four months. He initially noticed progressive, non-tender swelling of his cervical lymph nodes. This was accompanied by the development of drenching night sweats, profound fatigue that interfered with his daily activities and exercise routine, and unintentional weight loss, which he initially attributed to muscle loss from inactivity. He also reported experiencing a peculiar, intense itching sensation following warm showers or exposure to hot weather (aquagenic pruritus). His family history was notable for a first-degree relative who had passed away from lymphoma.

Initial Assessment

On initial workup, a cervical ultrasound confirmed the presence of multiple lymph nodes with abnormal features. An extensive panel for infectious etiologies was performed, with all results returning negative or within normal limits. A fine-needle aspiration (FNA) biopsy of a prominent cervical lymph node was conducted. The cytology showed reactive lymphoid cells; however, the sample cellularity was insufficient to perform flow cytometry for a more detailed immunophenotypic analysis. A complete blood count (CBC) performed one week prior to the current presentation showed a white blood cell (WBC) count of 11.5 x 10^9/L and a normal RDW of 11.7%.

The Diagnostic Journey

The patient presented for a follow-up with his hematologist. A repeat CBC was performed, which showed a significant change from the previous week's results. The key findings were:

• WBC: 4.0 x 10^9/L (a sharp decrease from 11.5)
• RBC: 3.9 x 10^12/L (mildly low)
• Hemoglobin: 11.5 g/dL (mild anemia)
• Hematocrit: 37.4%
• MCV: 91.4 fL (normocytic)
• RDW: 39.4% (a dramatic increase from 11.7%)
• Platelets: 206 x 10^9/L
• Absolute Neutrophil Count: 2.87 x 10^9/L
• Absolute Lymphocyte Count: 2.77 x 10^9/L

The most striking finding was the RDW of 39.4%, a value rarely seen outside of severe hematologic crises or significant laboratory error. This extreme anisocytosis was paradoxical given the patient's normocytic MCV. To rule out common causes of high RDW, further tests were checked, which revealed normal levels of ferritin (57 ng/mL), vitamin B12, and folic acid, making a nutritional deficiency anemia unlikely.

The patient's hematologist initially felt the constellation of findings was not concerning. However, the patient remained worried, questioning if the inconclusive FNA was sufficient to rule out lymphoma, especially given his persistent symptoms and the new, alarming lab results. The differential diagnosis centered on two main possibilities: 1) The extremely high RDW was a laboratory artifact, or 2) The patient's constitutional symptoms, combined with developing anemia and a volatile WBC, were indicative of an underlying lymphoproliferative disorder with potential bone marrow involvement.

Final Diagnosis

Unexplained Constitutional Symptoms and Cervical Lymphadenopathy, Concerning for Lymphoma; Awaiting Definitive Biopsy. The extreme elevation in RDW is considered a probable laboratory artifact pending confirmation with a repeat CBC and peripheral blood smear review.

Treatment Plan

The immediate diagnostic plan was formulated to address the clinical uncertainty:

1. Repeat CBC with Peripheral Smear: To verify the RDW value and have a pathologist manually review the morphology and size variation of the red blood cells. An extreme value like 39.4% is highly suggestive of an analytical error from the automated counter (coulter counter).
2. Excisional Lymph Node Biopsy: Given the persistent and classic B symptoms (night sweats, fatigue, weight loss), aquagenic pruritus, and the inconclusive nature of the FNA, an excisional biopsy of an entire lymph node was strongly recommended. This is the gold standard for diagnosing or ruling out lymphoma, as it provides tissue architecture necessary for accurate histopathological assessment.

Outcome and Follow-up

The patient is scheduled for a repeat CBC and a consultation with a surgeon to discuss an excisional biopsy. The primary clinical concern remains the possibility of an underlying lymphoma, such as Hodgkin lymphoma, which is common in this age group and aligns with the patient's symptom profile. The dramatic lab abnormality, while likely an artifact, served to escalate the urgency for a more definitive diagnostic procedure. Close follow-up is essential until a definitive diagnosis is established.