Solution to "An 85-Year-Old Woman With Pancytopenia"

Robert M. Centor, MD; Marilyn Ligon, MD

Disclosures

September 06, 2006

This is the solution to a case we presented recently. You may review the case here.

I used this Web page to review the differential diagnosis for pancytopenia: http://www.fpnotebook.com/HEM78.htm.

Key diagnoses to consider include aplastic anemia, myelophthisic anemia (infiltrating lesions caused by nonhematopoietic cells invading bone marrow), folate or B12 deficiency, paroxysmal nocturnal hemoglobinuria, systemic lupus erythematosus, myelofibrosis, multiple myeloma, and metastatic cancer.

The key test in this patient was triggered by her complete blood count (CBC). The data which I withheld was that her mean corpuscular volume (MCV) was 115, pointing to a likely megaloblastic anemia. The team measured a vitamin B12 level that was undetectable. Given her strict vegetarian history, we believe that she had developed B12 deficiency secondary to her dietary habits. She responded nicely to transfusions and B12 replacement.

If we had not diagnosed and suspected B12 deficiency, the next test would have been a bone marrow biopsy. When I first heard this presentation, I was ready to recommend a bone marrow biopsy, until I heard the MCV result.

The biggest clinical clue in her presentation comes from the neurologic exam. She clearly seemed more confused than her family remembered. She did have some decreased sensation in the lower extremities.

When I heard that this patient presented at Morning Report, the housestaff had not done a complete neurologic exam (and the patient had already been discharged). We would have expected to find dorsal and lateral spinal column damage. This presents classically with paresthesias and ataxia. On careful examination, patients have loss of vibration and position sense. Of note, vitamin B12 deficiency can progress to severe weakness and even paraplegia.

This presentation is most remarkable for its unremarkable presentation. We are not surprised when an 85-year-old woman presents with these nonspecific complaints. Her diagnosis reminds us that B12 deficiency should remain an important consideration in patients presenting with altered mental status or peripheral neuropathies. The diagnosis is most important because treatment is easy, inexpensive, and effective.

Read and participate in the discussion of this case here, and watch for another new case soon.

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