Occam's Razor and the Diagnosis of Mantle Cell Lymphoma

An 82-year-old gentleman presented with mid-epigastric pain over 3 months associated with nausea. His pain improved with eating, although he had been experiencing subtle weight loss over the past month. He denied any fevers. However, he did experience a single loose bowel movement. He carried no family history of blood dyscrasias or lymphomas, but did carry a family history of breast cancer. A complete blood cell count was ordered, which revealed a white blood cell count of 26,300/mm³. Given his abdominal pain and leukocytosis, a computed tomography scan of the abdomen was obtained, revealing inflammatory changes surrounding a colonic outpouching consistent with acute diverticulitis. He was started on antibiotics and his symptoms improved. A subsequent differential of his complete blood cell count returned showing 39% polymorphonuclear leukocytes, 11% lymphocytes, 1% monocytes, and 48% pathologic cells (Figure). A complete blood cell count 3 months prior showed a normal white blood cell count with a normal differential. Given the abnormal peripheral smear, a bone marrow biopsy was obtained revealing changes consistent with mantle cell lymphoma, blastoid variant, involving 40% of cells. There was normal maturation of the myeloid and erythroid series with megakaryocytes. The cells in the bone marrow were CD20 positive and cyclin D1 positive. The Ki-67 index was >90%. Cytogenetics were complex, including a p17 deletion, but without the typical translocation seen in mantle cell lymphoma.

Over the ages, multiple philosophies in diagnostic medicine have surfaced, including Saint's Triad and Hickam's dictum. These both advocate for multiple separate diagnoses to arrive at an explanation vs Occam's razor advocating for diagnosis solidarity. As physicians, we often recognize a pattern and attempt to coalesce a patient's presenting symptoms into a unifying diagnosis. Although a diagnosis may seem clear, it is necessary to perform a thorough work-up to exclude less common or concomitant etiologies. Ultimately, this patient was diagnosed with a rare variant of mantle cell lymphoma. He had a seemingly straightforward diagnosis of diverticulitis based on history, physical examination, and imaging. In agreement with Occam's razor, diagnostic work-up would have ceased upon arrival at the initial diagnosis. Furthermore, in retrospect, the patient possessed few risk factors for lymphoma, including only age and sex, but no family history of hematologic malignancies. He did, however, present with subtle weight loss that would not be typical of diverticulitis alone. With modern medicine's increasing proclivity for cost cutting and waste reduction, the “shotgun” approach to diagnostic testing is no longer practical or appropriate. A minimal number of targeted tests arrived at a clinically sound diagnosis of diverticulitis. However, had the work-up stopped, the insidious diagnosis would have been missed. Simplicity and thrift should not preclude thoroughness. This case illustrates the importance of a comprehensive diagnostic work-up when the possibilities of additional etiologies still exist. In this case, a differential of the elevated white blood cell count was reasonable and should constitute a crucial step in the overall diagnostic decision tree whenever evaluating for leukocytosis.

In the modern era of medicine, diagnostic parsimony is sought often, coinciding with the rationalization of health care resources. A single diagnosis should not be the be-all and end-all, especially with the current state of patients living longer and often carrying with them a multitude of illnesses that come with age.