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44 Part I: Clinical Evaluation of the Patient Chapter 4: Consultative Hematology 45

Leukocytosis refers to an elevated total leukocyte count. When EOSINOPHILIA
combined with an elevated ANC, the term neutrophilic leukocytosis Eosinophilia has a daunting differential, as discussed in Chap. 62.
is used. If an elevated ANC is present without leukocytosis, the term On initial screen, we seek to identify patients with moderate (>1500
neutrophilia is applied. The same terminology holds for elevations of cells/μL) or greater eosinophilia, or those with evidence of end organ
the lymphocyte, monocyte, eosinophil, and basophil compartments. damage, as these groups are more likely to have serious pathology.
In practice, however, these distinctions are rarely made, nor do they The history should include assessment of B symptoms, rash, diarrhea,
have a major impact on diagnostic evaluations, and thus we use them allergic symptoms, travel history, and food intake. Ingestion of raw or
interchangeably.
undercooked meat, especially pork, increases the chance of parasitic
infection with Trichinella spiralis, which may be accompanied by signifi-
NEUTROPHILIA cant eosinophilia, periorbital edema, myositis, and fever. This infesta-
Neutrophilia may be seen in a variety of settings as outlined in tion usually occurs at festivities where a pig is roasted and served. Pork
Chap. 65. Primary marrow disorders include chronic myelogenous from abattoirs involves mixing of meat from a large number of pigs,
leukemia (CML), other myeloproliferative neoplasms, neutrophilic leu- diluting the Trichinella organisms that might have infected a rare ani-
kemia, and sickle cell disease. Secondary disorders include infection, mal. The geographic location and lifestyle of the patient determines if
inflammation, smoking, stress (both physical and emotional), asplenia, consideration of another parasitic infestation is a high probability. In
and medications. With respect to the latter, common offenders include underdeveloped countries, helminthic infections are the most com-
corticosteroids, lithium, and exogenous growth factors such as granu- mon cause of eosinophilia (see Chap. 62, Table 62–5 for causes of hel-
locyte colony-stimulating factor. Rare cases of dramatic neutrophilia minthic-induced eosinophilia). Signs of adrenal insufficiency (fatigue,
(usually accompanied by mild anemia) can be associated with granu- hypotension, hyperpigmentation) a rare cause of eosinophilia, may be
locyte colony-stimulating factor–secreting tumors (e.g., bronchogenic subtle. Rhinosinusitis, asthma, and eosinophilia should trigger screen-
carcinoma). In a patient with persistent neutrophilia of unclear etiology, ing for eosinophilic granulomatosis with polyangiitis (Churg-Strauss
it is generally advisable to exclude CML with a qualitative breakpoint syndrome). Mast cell disorders are also associated with eosinophilia,
cluster region-Abelson (BCR-Abl) polymerase chain reaction (PCR) and should be kept in mind in patients with a rash suggestive of urti-
analysis. The other classic myeloproliferative neoplasms (MPNs), such caria pigmentosa or symptoms of mediator release with identified trig-
as polycythemia vera (PV), essential thrombocythemia (ET), and mye- gers. Patients with extreme eosinophilia are often critically ill and nearly
lofibrosis, will typically have other manifestations suggesting the diag- always require hospitalization because of the high probability of malig-
nosis, such as erythrocytosis, thrombocytosis, organomegaly, and/or a nancy or infection, in addition to risks for life-threatening damage to
leukoerythroblastic blood film. Chronic neutrophilic leukemia (CNL), the cardiac, respiratory, nervous, and gastrointestinal systems.
though often considered by clinicians, is a rare disorder. The WBC
should be greater than 25,000/μL of which greater than 80 percent are BASOPHILIA AND MONOCYTOSIS
neutrophils to consider this entity. Disorders associated with basophilia and monocytosis are more limited,
Smokers commonly demonstrate a mild neutrophilia, and if this has and are listed in Chaps. 63 and 70, respectively. In the absence of an
been longstanding in an otherwise asymptomatic patient, further mea- obvious infectious/inflammatory insult, basophilia should always trig-
sures other than smoking cessation are typically unnecessary. Similarly, ger evaluation for CML and PV. Unexplained monocytosis, particularly
mild neutrophilic leukocytosis may be seen in obese patients, perhaps in elderly patients with other cytopenias, should reflex concern for mye-
reflective of an underlying inflammatory state. It is rarely useful to perform loid malignancies such as MDS and chronic myelomonocytic leukemia
a marrow examination for neutrophilia during times of systemic infection (CMML) and generally warrants examination of the marrow.
or critical illness in the intensive care unit, except for the rare instance in
which neutrophilia is felt to be the proximate illness, as in CNL.
ERYTHROCYTOSIS/POLYCYTHEMIA
LYMPHOCYTOSIS As opposed to hematologic consultation for the cytopenias, evaluation

The diverse causes of lymphocytosis are listed in Chap. 79. Primary for polycythemia generally has a more limited differential diagnosis
marrow disorders include chronic lymphocytic leukemia (CLL), acute (Chaps. 57 and 84). Technically, “polycythemia” refers to increases in
lymphoblastic leukemia (ALL), and hairy cell leukemia. Reactive RBC, WBC, and platelets, while “erythrocytosis” more specifically refers
lymphocytosis may be seen in viral infection (classically infectious to increases in RBCs alone. We are aware, however, that in common
mononucleosis), HIV, bacterial infection, smokers, and autoimmune hematologic parlance the term polycythemia is frequently used to indi-
disorders (such as rheumatoid arthritis). cate erythrocytosis and here we use them interchangeably. The disor-
Lymphocyte morphology is generally more informative than is the ders that may cause polycythemia are diverse and have widely varying
case in neutrophilia. If the lymphocytes display coarse, clumped chro- treatments. Attention to detail is critical.
matin, suspicion is raised for CLL. Readily identifiable lymphoblasts First, the distinction between absolute and relative polycythemia
suggest ALL. An excess of large granular lymphocytes, particularly in a should be made. The former refers to a true elevation of the red cell
patient with autoimmune disease such as rheumatoid arthritis, suggest mass, whereas the latter refers to an apparent increase in hemoglobin
large granular lymphocytic (LGL) leukemia. The presence of lympho- caused by a contracted plasma volume. Reduced plasma volumes might
cytes with villous projections might suggest splenic marginal zone lym- be seen in patients who are dehydrated and are also reported in chronic
phoma or hairy cell leukemia. Larger lymphocytes with cleaved nuclei smokers. However, smokers are more often polycythemic by virtue of
may be seen in follicular lymphoma, and cells with cerebriform nuclei their cardiopulmonary disease, so this distinction is difficult to make.
might represent the malignant T cells of Sézary syndrome. Hence, When evaluating a referral for elevated RBC, hemoglobin, or
examination of the blood film is a critical component of the lympho- hematocrit, one begins by determining which measure is elevated.
cytosis evaluation. The laboratory evaluation might also include flow Although definitions vary, one may assume polycythemia is present
cytometric analysis, as the immunophenotype of atypical lymphocytes if the hemoglobin is greater than 18.5 g/dL in men or greater than
often leads to significant narrowing of the differential diagnosis. 16.5 g/dL in women.

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