What is marrow reconversion

Consequently, colonoscopy examination was performed which indicated that the tumor was located about 6 cm away from the anus.

Pathological examination of the tissue showed evidence of rectal adenocarcinoma. For further evaluation, whole body bone scintigraphy with 99 mTc-methylene diphosphonate 99 mTc-MDP was performed on April 6th, and revealed abnormal radiotracer uptake in the pelvis, especially in sacroiliac joint, which suggested metastatic disease Figure 2.

Ultimately, the diagnosis of BMR was histopathologically confirmed by a bone marrow biopsy of the ilium, which was performed on April 12th and revealed erythroid hyperplasia rather than bone marrow metastasis. Generally, in a healthy person, the bone marrow undergoes conversion from hematopoietically active red marrow to hematopoietically inactive yellow marrow in a very orderly and predictable pattern 9.

This conversion is from distal to proximal, from the appendicular to the axial skeleton and from the diaphyses of the long bones toward the metaphyses 9. Increased demand for hematopoiesis prompts reconversion from fatty marrow to active red marrow, and the reconversion process occurs in the exact reverse order: centripetally from the axial to the appendicular skeleton 2.

BMR can be a consequence of both non-medical conditions e. In our case, since the primary tumor in the upper rectum was relatively large, and the patient had a 2-year history of constipation and severe anemia, we deemed that rectal cancer had developed over the past 2 years. In addition, during the 2-year history of anemia, the patient did not receive medical treatment for anemia and she just took food supplements.

In this report, we described the rectal cancer patient with pelvic MRI features mimicking pelvis metastases due to BMR, which was attributed to chronic anemia. MRI is the most sensitive imaging modality that evaluates the bone marrow. The signal intensity depends on the relative amount of protein, water, fat, and cells within the marrow Yellow marrow appears hyperintense on T1-weighted images, because it is composed of fatty elements, and it shows intermediate response to high signal intensity on T2-weighted images.

It saturates similarly to subcutaneous fat on T2-weighted sequences with fat saturation and on STIR sequences. Reconversion also was found to be more prevalent in patients less than 39 years old and in obese women who smoked. No association was found between weight, sex, or obese male smokers and reconversion.

Conclusion: Our results show marrow reconversion at the knee is most prevalent in heavy smokers, younger patients, and especially obese women who smoke heavily. In these patients, marrow reconversion can be a normal finding on MR imaging. The halo sign, characterized by a rim of bright signal intensity on T2-weighted images, may indicate the presence of malignancy [ 14 ]. Infection i. In the current series, multi vertebral signal intensity and the absence of clinical signs of infection excluded infection in all seven patients.

Several clinical characteristics were associated with the diffuse appearance of red bone marrow in this series. Most patients in this series were elderly, with an average age of Although, all patients had a history of back pain, the pain resolved and was thus not considered in the association analysis.

Moreover, non-specific low back pain might not explain MRI abnormality in the whole spine. Four patients had a history of cancer. The association between cancer and reconversion is unknown, because patients with a history of cancer tend to have extensive investigations, and thus have a higher probability of identifying reconversion.

Most patients in this series had mild anemia. Red bone marrow reconversion occurs when oxygen requirements increase [ 5 , 6 ]; hence, compensation by reconversion may have occurred leading to mild anemia. A heavy smoking history has been significantly associated with marrow reconversion [ 7 ]. Chronic smoking may result in tissue hypoxia because of elevated carboxyhemoglobin levels [ 7 ]. In our series, heavy smoking, having more than 20 cigarettes a day, was seen in six out of seven cases.

Thus, heavy smoking appears to be associated with reconversion. However, one female patient had no history of smoking, and was otherwise healthy. Further investigation of such cases is required to understand the as-yet-unidentified factors associated with reconversion. The diagnosis of bone marrow reconversion on MRI can be made by comparison of red bone marrow intensity to that of the spinal cord and by comparison of the yellow bone marrow intensity to that of the retroperitoneal fat.

Mild anemia was seen in most cases and may be a compensated condition. The association of bone marrow reconversion with cancer is unknown, but heavy smoking might be related to the condition. All patients represented in this study were informed that the data from their case would be de-identified and used in a journal publication. Charles J. Malemud received the Ph. Since , Dr. He has published over papers, chapters and reviews primarily in the field of chondrocyte biology.

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They offer accessible information to a wide variety of individuals, including physicians, medical students, clinical investigators, and the general public. They are an outstanding source of medical and scientific information. Indeed, the research articles span a wide range of area and of high quality. This is specially a must for researchers belonging to institutions with limited library facility and funding to subscribe scientific journals.

They provide easy access to the latest research on a wide variety of issues. Relevant and timely articles are made available in a fraction of the time taken by more conventional publishers. Articles are of uniformly high quality and written by the world's leading authorities. In part I of this review, we discussed marrow conversion and reconversion, as well as disorders of marrow depletion and important but miscellaneous processes which are otherwise difficult to categorize.

In part II of our review, additional marrow conditions such as bone marrow edema, infiltration, and replacement; myeloproliferative disease; and marrow ischemia will be discussed. The views expressed in this material are those of the author, and do not reflect the official policy or position of the U.

Wang DT. J Am Osteopath Coll Radiol. Wang, D. Normal Marrow Normal bone marrow is composed of variable proportions of hematopoietic cells and fat. Childhood marrow one year to 10 years Near the end of the first year of life, marrow conversion begins in the phalanges of the hands and feet and is complete by 1 year of age.

Adult marrow over 25 years By the middle of the third decade, the mature or adult pattern of marrow is achieved with yellow marrow predominating throughout the appendicular skeleton, except for the proximal metaphyses of the femora and humeri figs.

Marrow Conversion in the Axial Skeleton The axial skeleton includes the spine, ribs, sternum, skull, and pelvis. Aplastic Anemia The earliest description of aplastic anemia was by Erlich in who published a case of a young pregnant woman who presented with bleeding, fever, and severe anemia.

Radiation The medical uses of ionizing radiation include the treatment of various cancers, such as multiple myeloma and metastatic disease. Early after chemotherapy, marrow appears hypointense on T1 weighted images and hyperintense on fat-suppressed T2 and STIR images owing to marrow congestion. Osteopetrosis Osteopetrosis is a hereditary skeletal dysplasia characterized by abnormal osteoclastic activity, resulting in a generalized pattern of diffusely increased bone density.

Gaucher Disease The most common of the lysosomal storage diseases, Gaucher disease is characterized by a deficiency of glucocerebrosidase, which results in abnormally high levels of glucocerebroside that is taken up by histiocytes termed Gaucher cells. Iron Storage Disease Deposition of iron in marrow occurs in conditions where there is increased breakdown of erythrocytes such as sickle cell anemia or thallassemia , iron overload as in those who are on chronic blood transfusion therapy , or when there is overall abnormal absorption such as in primary hemochromatosis.

Serous Atrophy or Gelatinous Transformation In patients with profound loss of body fat stores, as in patients who have severe cachexia, anorexia nervosa, or acquired immunodeficiency syndrome, a phenomenon known as serous atrophy or gelatinous transformation of the bone marrow can occur.

Summary In conclusion, interpretation of marrow on MRI requires an understanding of the normal pattern of marrow maturation or conversion, as well as an understanding of how the hematopoietic and fatty constituents of marrow contribute to the normal MRI appearance. References Travlos GS. Toxicologic Pathology ; Bone Marrow Imaging. Radiology ; Structure of the marrow and the hematopoietic microenvironment. Magnetic resonance imaging of the normal bone marrow. Skeletal Radiology ; Red and yellow marrow in the femur: age-related changes in appearance at MR imaging.

Pediatric Musculoskeletal MR Imaging. Andrews CL. Evaluation of the Marrow Space in the Adult Hip. Radiology ; SS Scott MW. Zerhouni EA. Magnetic Resonance imaging of normal bone marrow. European Radiology ; Guillerman RP. Thomas L. Skeletal Radiology ; Am J Roentgenol.

MRI of the marrow in the paediatric skeleton. Clinical Radiology ; Bone marrow imaging in children. Duda SH. Magnetic resonance imaging of bone marrow: diagnostic value in diffuse hematologic disorders. Magn Reson Q ;