And the Oscar goes to peripheral blood film for detection of lead poisoning in a complicated toxic patient: A case report with review of laboratory clues

PBS provides the hematologic and/or non-hematologic picture of a case.A
40-year-old man with history of alcohol and marijuana abuse presented
with extremities and abdominal pain.After extensive investigations,
finding basophilic stippling on PBS led to the diagnosis of lead
poisoning.PBS is the simplest screening test which provide rich
morphological information.


Background
A manual blood smear review is defined as the thorough and careful microscopic analysis of a well-prepared and stained smear of the peripheral blood, with the objective of seeking morphological changes relevant to the diagnosis and monitoring of patients (1). Laboratoryinitiated examinations of blood smears for patients with anemia are usually the result of a laboratory policy according to which a blood smear is ordered whenever the hemoglobin concentration is unexpectedly low. In these cases, despite the wealth of the captured information from modern automated cell counters including red-cell count, mean cell volume(MCV), mean cell hemoglobin(MCH), mean cell hemoglobin concentration(MCHC) and red-cell-distribution width(RDW), there are still morphologic abnormalities that are critical in the differential diagnosis of anemia and can be determined only from a blood smear. Particularly important is the detection of variations in the cell shape and of red-cell inclusions, such as Howell-Jolly bodies, Pappenheimer bodies and basophilic stippling or punctate basophilia. The last could suggest lead poisoning in the setting of matched clinical data (2).

Case presentation
A 40-year-old man was transferred to our center at Abu Ali Sina Hospital, Shiraz, Iran, to be evaluated for severe bone pain and abdominal pain for a month with worsening since 1 week ago. The bone pain was mostly limited to lower extremities and the abdominal pain was severe with colicky pattern and radiation to both scrotums. It was accompanied by nausea, vomiting and constipation. The patient was also complaining of severe weight loss (15 kg during a month). He was a fast food employee with history of excessive alcohol intake over 3 years, with no periods of abstinence. He was drinking 1-2 liters of homemade alcohol (using traditional container for distillation) daily until few days prior to admission. Additionally, he reported a history of on and off synthetic marijuana abuse till 3 days prior to admission. His past medical history was not significant and he was not taking any medication. His physical examination was significant for high blood pressure (180/100 mmHg), tachycardia (108/min) and low grade fever (37.9°C) with abdominal and both scrotal tenderness.
Laboratory investigations at presentation showed moderate microcytic and hemolytic anemia in addition to significantly elevated liver enzymes. Abdominopelvic sonography and CT scan showed biliary sludge and small liver hemangioma, respectively. Other laboratory and imaging investigations (color doppler sonography of mesenteric artery and vein, upper gastrointestinal endoscopy, colonoscopy) were unremarkable. He underwent cholecystectomy with the impression of acute cholecystitis and the microscopic pathologic diagnosis was just chronic cholecystitis without cholelithiasis. Due to the presence of unexplained anemia and severe bone pain, bone marrow study was done for him to rule out of leukemia, which was in favor of myelodysplastic syndrome (MDS) with 10% ring sideroblasts ( Figure 1). Cytogenetic study was normal. Complete blood count (CBC) test with peripheral blood smear (PBS) checking (according to our policy in the hematology laboratory) was done for the patient several times at presentation and during hospitalization. Blood film examinations revealed mild to moderate anemia, microcytic hypochromic red blood cells with, anisocytosis, polychromasia and also frequent coarse basophilic stippling of the red cells (Figure2 A, B); the last one was missed at the first PBS review. Regarding the presence of ring sideroblasts in the bone marrow report, the possibility of lead poisoning was considered and surprisingly the blood lead level was markedly raised (151 µg/dL; reference range was 10 µg/dL). Since there was no occupational exposure, the traditional distillation dish (made of copper and lead) was traced as the possible source of the lead.
The patient stopped drinking alcohol and marijuana abuse. Chelating therapy with Succimer was initiated, with a dose of 500 mg (5 capsules) daily and now after 4 weeks the blood lead level has declined to 25 µg/dl and there is 6 kg weight gain. All signs and symptoms were removed and all laboratory findings changed to normal condition. Although there are some documented researches supporting the correlation between hypertension and lead poisoning, in our case, marijuana withdrawal could also be the cause of sympathetic overactivity(3). Table 1 shows the transition of laboratory data from the first presentation to recovery time.

Discussion
CBC is the most commonly ordered test in hospitalized patients. Modern automated blood cell counters produce a detailed report on the red cells, white cells and platelet, with differential white blood cell counts. A drop of the remaining blood could then be smeared and stained (4). Microscopic examination of this smear under expert eye yields useful information and further details regarding all formed elements of the blood (5). "More information can be gained from examining the blood smear than from any other single hematologic procedure", Jandl in 1987 said (6). This shows the value of PBS review in the medical management. Initiation of a PBS review depends on the laboratory policy. It could be a clinical request by the attending clinician on the account of a clinical suspicion or initiated by the laboratory due to clinical information, numerical deviations in the automated counts, flags raised by the analyzers or based on a designed protocol in the laboratory(based on workload of the laboratory) (4,7). For certain disorders, for instance hematologic malignancies or parasitic infestations, examination of the PBS can be diagnostic. For others such as our case, the PBS provides important clues in the clinical management and determines which diagnostic tests are indicated (2).
Among all useful data obtained from the blood smear, there is valuable information about the red blood cell size, shape, staining (color) and intracellular inclusions. Red cell inclusions often result from defective maturation of the erythrocytes, oxidant injury to the cells or infections and are almost always indicative of some sort of pathology. Basophilic stipplings (punctuate basophilia) are well-known red cell inclusions. In fact they are denatured RNA fragments dispersed within the cytoplasm (7). They are present as irregular basophilic granules which stain deep blue with Wright's stain. They vary from fine to coarse. Fine stippling is commonly seen with increased production of the red cells. Coarse stippling may be seen in haemoglobinopathies (thalassemias), sideroblastic anemia, megaloblastic anemia, and a rare inherited condition, pyrimidine 5' nucleotidase deficiency. Sideroblastic anemia is characterized by accumulation of iron in the mitochondria, which appears as ring distribution around the nucleus of the erythroid precursors on iron stain. Sideroblastic anemia occurs as primary or secondary (5,7).
Lead poisoning is an important cause of secondary sideroblastic anemia because environmental exposure to lead is usually unrecognized and needs to be detected (5). Lead exposure usually occurs through contaminated air and food. Excess lead affects almost every organ in the body. The major anatomic targets are the blood (bone marrow), nervous system, gastrointestinal tract, and kidneys. Lead has a high affinity for sulfhydryl groups and interferes with the enzymes involved in heme synthesis. Iron incorporation into heme is impaired, leading to microcytic hypochromic anemia with distinctive punctate basophilic stippling of the red cells. Lead also inhibits sodium-and potassium-dependent ATPases in the cell membranes, an effect that may increase the fragility of red cells, causing hemolytic anemia (8).
The classic form of lead neuropathy consists of weakness that primarily involves the wrist and finger extensor (wristdrop and footdrop). Excess lead could induce "lead lines" formation in epiphyses of the bone and gum. The gastrointestinal tract is also a locus for major clinical manifestations. Lead "colic" is characterized by extremely severe, poorly localized abdominal pain and finally since the excretion of lead occurs through the kidneys, exposures may cause damage to the proximal tubules, interstitial fibrosis and possibly renal failure (8).
Since lead poisoning is a condition with potential multiorgan damage, it can be traced in the human body with variable laboratory tests. The half-life of lead in the blood and bone is 35 days and 32 years, respectively, so the blood lead level just reflects the current and recent exposure (5,9). Table 2 shows different laboratory tests, their properties and changes in cases of lead poisoning. Elevated blood lead (> 10 µ/dL) and red cell free protoporphyrin levels (> 50 µg/ dL) or, alternatively, zinc-protoporphyrin levels, are required for definitive diagnosis (5). Impairment of the hematological system is one of the earliest signs of lead accumulation and could be characteristic. Even in milder cases of lead exposure, anemia may be the only obvious abnormality (5). Obviously, the PBS is the fastest, simplest and cost-effective test which could also be made and examined at emergency and screening rooms at hospitals and could prevent unnecessary laboratory tests and other invasive diagnostic procedures including inappropriate laparatomy (13). Since this process is among the most time-consuming ones in hematology laboratories and requires high technical competence to minimize the errors of subjectivity, each laboratory should make its own policy to review the blood smears. Clearly providing clinical data including occupational and environmental health history through communication between the clinicians and the laboratory team could lead to a more rapid and accurate diagnosis (14).
Our patient was a case of chronic lead poisoning with atypical symptoms and signs, such as severe bone pain and highly elevated liver enzymes which caused delayed diagnosis. In this case, a lot of laboratory and imaging work ups including hematologic tests (and also the initial PBS) failed to reach a correct diagnosis, while the second PBS review by an expert clarified the long and painful story. We believe that even the first PBS review may discover the problem if it is reviewed accurately and/or is provided with typical clinical data.

Conclusion
This case emphasizes that all patients with unknown disease should be evaluated in terms of PBS at the first work up and the PBS in all patients (hematologic and non-hematologic) should be reviewed systematically regarding all blood elements. Lead poisoning is more common than our estimation. As clinical manifestations are non-specific and may be misdiagnosed with other pathophysiological conditions, at least it should be included in differential diagnosis lists of adult unexplained anemia (especially in the setting of matched clinical data) and basic initiative laboratory tests such as PBS could rule out the need for invasive, expensive and time consuming procedures.

Ethics approval and consent to participate
Our institutional approval was not required to publish the case details.