- Email: [email protected]
2-Deoxy-2-[18F]Fluoro-D-Glucose Positron Emission Tomography Uptake in a Giant Adrenal Myelolipoma
PII S1536-1632(02)00018-5
Molecular Imaging and Biology Vol. 4, No. 5, 355–358. 2002 Copyright © 2002 Elsevier Science Inc. Printed in the USA. All rights reserved. 1536-1632/02 $–see front matter
BRIEF ARTICLE
2-Deoxy-2-[18F]Fluoro-D-Glucose Positron Emission Tomography Uptake in a Giant Adrenal Myelolipoma Vinicius Ludwig, MD, Michael H. Rice, MD, William H. Martin, MD, Mark C. Kelley, MD, Dominique Delbeke, MD, PhD Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN Incidental adrenal lesions found on anatomic imaging are not uncommon. 2-Deoxy-2[18F]fluoro-D-glucose positron emission tomography (FDG-PET) imaging is highly accurate in the differentiation of benign from malignant adrenal lesions, both in patients with proven malignancy and with adrenal lesions detected incidentally. A 60-year-old white female with a history of lower mid-back pain underwent computerized tomography (CT) imaging that identified a 15-cm complex mass within the left adrenal gland with soft tissue, cystic, and adipose components. FDG-PET imaging showed significant hypermetabolic activity within portions of the mass with central photopenia suggesting a malignant lesion with central necrosis. Surgical excision and pathological examination, however, revealed a benign adrenal myelolipoma with extensive adenomatous and hematopoietic elements. Prior reports of adrenal myelolipoma evaluated with FDG-PET imaging have described no significant FDG uptake within these benign tumors. This case is an unusual example of histologically proven benign adrenal myelolipoma that was hypermetabolic on FDG-PET imaging. Correlation of pathologic and imaging findings demonstrated that the hypodense regions on CT were hypometabolic on FDG-PET and corresponded to cystic necrosis and adipose elements, whereas the adenomatous and hematopoietic elements were hypermetabolic.(Mol Imag Biol 2002;4:355–358) © 2002 Elsevier Science, Inc. All rights reserved. Key Words: Whole-body PET; FDG; Adrenal myelolipoma.
Introduction
Case Report
U
A 60-year-old white female presented with a history of non-specific lower mid-back pain with no prior history of malignancy. An MRI of the lumbar spine showed a large mass in the left retroperitoneum, confirmed by a CT of the abdomen. On CT, this 15-cm heterogeneous mass (Figure 1) contained cystic, solid, and adipose components that appeared to be arising within or adjacent to the left adrenal gland. Calcification was also present within the lesion. The patient had no symptoms of hormone excess or catecholamine hypersecretion. Portions of the mass were markedly hypermetabolic on 2-deoxy-2-[18F]fluoro-D-glucose positron emission tomography (FDG-PET) imaging (Figure 2) with several central areas of photopenia suggestive of malignancy with central necrosis. The surgically resected lesion revealed weighed 610 g and measured 15 x 13 x 10 cm. Macroscopic examination of the gross specimen (Figure 3) revealed a round, well-encapsulated soft tissue mass with a 3 0.5-cm rim of pale yellowish tissue along one aspect, a tan-reddish brown parenchyma with a prominent off-center area of red marrow mea-
nexpected adrenal lesions are often found on computerized tomography (CT) or magnetic resonance imaging (MRI) imaging performed for suspected abdominal disease. Most adrenal lesions are likely to be benign, even in patients with known primary extra-adrenal malignancy.1 Benign adenomas are the most common cause of nonfunctioning adrenal lesions. The incidence of adrenal myelolipoma at autopsy varies from 0.08–0.2%.2 Histologically, they are benign neoplasms composed of mature adipose tissue and hematopoietic elements.3–5 These benign adrenal lesions usually remain small and asymptomatic; however, they occasionally reach massive proportions and become symptomatic, resulting in non-specific complaints generally related to mechanical compression of adjacent organs.
Address correspondence to: Dr. Dominique Delbeke, Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, 21st Avenue South & Garland, Nashville, TN 37232-2675. Email: [email protected]
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356 Molecular Imaging and Biology, Volume 4, Number 5
Figure 1. A CT scan of the abdomen demonstrated a 15-cm complex left adrenal mass containing soft tissue, cystic, and adipose components based on Houndsfield unit measurements.
suring about 7 cm in dimension, and cystic areas filled with yellow clear fluid. Microscopic examination (Figure 4) revealed that the lesion was arising from the adrenal cortex and had extensive adenomatous changes, including large cortical cells with abundant eosinophilic cytoplasm, large nuclei and prominent nucleoli indicating polyploidy. Foci of osseous metaplasia, adipose tissue with cystic necrosis and abundant hematopoietic elements were also identified. These findings were diagnostic of a benign adrenal myelolipoma. Correlation of the pathologic and imaging findings revealed that the hypodense regions on CT scan were hypometabolic on FDG-PET images and corresponded to cystic necrosis and adipose elements on the histologic section. The more dense regions on CT scan were
Figure 2. Transaxial (A) and coronal (B) FDG-PET images demonstrated a large hypermetabolic lesion with central regions of photopenia, usually indicative of a malignant tumor with central necrosis and/or hemorrhage. In this case, however, the hypermetabolism corresponded to the hematopoietic and adenomatous elements, while the hypometabolism corresponded to cystic necrosis and adipose elements.
hypermetabolic on FDG-PET images and represented the hematopoietic and adenomatous elements on the histologic section.
Discussion In this case, a 15-cm adrenal myelolipoma demonstrated areas of marked FDG uptake in a pattern suggestive of a metabolically active malignant neoplasm.
DG Uptake in Giant Adrenal Myelolipoma / Ludwig et al. 357
Figure 3. Photograph of the cut section of the left retroperitoneal mass shows a 15-cm well-encapsulated soft tissue mass with a 3 0.5-cm rim of adrenal tissue and focal cystic irregularities filled with yellow clear fluid. The yellowish-brown areas corresponded to adipose tissue, whereas the reddish regions were indicative of hematopoietic elements.
To our knowledge, the few reported cases of adrenal myelolipoma that have been imaged with FDG-PET have shown no significant FDG uptake.6 Adrenal myelolipoma is a benign neoplastic lesion composed of mature adipose tissue admixed with hematopoietic elements in various proportions. The age range of patients with adrenal myelolipoma is 17 to 93 years, with an average age at diagnosis of 50 years, it is rare in individuals under 30 years of age. Myelolipomas are usually non-secreting but have been associated with a variety of endocrine disturbances, including Cushing’s syndrome (combined with an adrenal cortical adenoma), pituitary-dependent Cushing’s disease, Addison’s disease, virilism, and pseudo-hermaphroditism. The color varies from pale yellow to deep red or reddish-brown depending upon the relative proportions of adipose and hematopoietic elements. Occasionally, infarct or hemorrhage occurs with secondary hematoma formation or fibrosis. Rarely, foci of ossification are seen, as in this case. On CT imaging, myelolipomas are usually well-circumscribed with a variable appearance depending upon the proportion of adipose tissue present. Lesions with little or no adipose tissue may be difficult to distinguish from other adrenal tumors. On MRI, the adipose components tend to have a typical bright appearance on T1-weighted images with signal drop-out on fat saturation sequences. Recently FDG-PET imaging has shown great potential in differentiating benign from malignant adrenal lesions with a sensitivity of 100%, specificity of 94%, and accuracy of 96%.6–8 In patients with known malignancy, FDG-PET has the additional potential of dem-
Figure 4. A whole mount histologic section illustrates the adenomatous elements (blue), adipose elements (white), and hematopoietic elements (red) of the tumor consistent with a benign adrenal myelolipoma.
onstrating unsuspected extra-adrenal and distant metastases.6 The most common benign and malignant tumors of the adrenal gland are adenomas and metastases, respectively. Benign adenomas are usually not FDG-avid, although occasional cases of hypermetabolic benign adrenal adenomas have been reported.7,8 Among the primary tumors that can arise from the adrenal gland, adrenal carcinomas are usually markedly FDG-avid. The degree of FDG uptake of neuroendocrine tumors is more variable and may be related to their degree of differentiation.9 Most malignant, and approximately 50% of benign pheochromocytomas accumulate FDG.10
Conclusion This case is an unusual example of histologically proven benign adrenal myelolipoma with extensive adenomatous changes and hematopoietic elements that were hypermetabolic on FDG-PET imaging.
References 1. Abrams, H.L.; Spiro, R.; Goldstein, N. Metastases in carcinoma: analysis of 1000 autopsied cases. Cancer 3:74–85; 1950. 2. Enzimer, F.M.; Sharen, W.W. Benign lipomatous tumors. In: Enzimer, F.M., Sharen, W.W., eds. Soft tissue tumors. 3rd ed. St. Louis:Mosby; 1995: pp 409–410. 3. Yildiz, L.; Akpolat, I.; Erzurumlu, K.; et al. Giant adrenal myelolipoma: case report and review of the literature. Pathol. Int. 50:502–504; 2000. 4. Vara Castrodeza, A.; Madrigal Rubiales, B.; Veiga Gonzalez, M.; et al. Adrenal gland myelolipoma: radiological review. Arch. Esp. Urol. 54:73–76; 2001.
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5. O’Daniel-Pierce, M.E.; Weeks, J.A.; McGrath, P.C. Giant adrenal myelolipoma. South Med. J. 89:1116–1118; 1996. 6. Maurea, S.; Klain, M.; Mainolfi, C.; et al. The diagnostic role of radionuclide imaging in evaluation of patients with nonhypersecrating adrenal masses. J. Nucl. Med. 42: 884–892; 2001. 7. Yun, M.; Kim, W.; Alnafisi, N.; et al. 18F-FDG PET in characterizing adrenal lesions detected on CT or MRI. J. Nucl. Med. 42:1795–1799; 2001. 8. Erasmus, J.J.; Patz, E.F. Jr; McAdams, H.P.; et al. Evalua-
tion of adrenal masses in patients with bronchogenic carcinoma using 18F-fluorodeoxyglucose positron emission tomography. AJR 168:1357–1360; 1997. 9. Erasmus, J.J.; McAdams, H.P.; Patz, E.F.; et al. Evaluation of primary pulmonary carcinoid tumors using FDG PET. AJR 170:1369–1373; 1998. 10. Shulkin, B.L.; Thompson, N.W.; Shapiro, B.; et al. Pheochromocytomas: imaging with 2-[fluorine-18]fluoro-2deoxy-D-glucose PET. Radiology. 212:35–41; 1999.
Molecular Imaging and Biology Vol. 4, No. 5, 355–358. 2002 Copyright © 2002 Elsevier Science Inc. Printed in the USA. All rights reserved. 1536-1632/02 $–see front matter
BRIEF ARTICLE
2-Deoxy-2-[18F]Fluoro-D-Glucose Positron Emission Tomography Uptake in a Giant Adrenal Myelolipoma Vinicius Ludwig, MD, Michael H. Rice, MD, William H. Martin, MD, Mark C. Kelley, MD, Dominique Delbeke, MD, PhD Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN Incidental adrenal lesions found on anatomic imaging are not uncommon. 2-Deoxy-2[18F]fluoro-D-glucose positron emission tomography (FDG-PET) imaging is highly accurate in the differentiation of benign from malignant adrenal lesions, both in patients with proven malignancy and with adrenal lesions detected incidentally. A 60-year-old white female with a history of lower mid-back pain underwent computerized tomography (CT) imaging that identified a 15-cm complex mass within the left adrenal gland with soft tissue, cystic, and adipose components. FDG-PET imaging showed significant hypermetabolic activity within portions of the mass with central photopenia suggesting a malignant lesion with central necrosis. Surgical excision and pathological examination, however, revealed a benign adrenal myelolipoma with extensive adenomatous and hematopoietic elements. Prior reports of adrenal myelolipoma evaluated with FDG-PET imaging have described no significant FDG uptake within these benign tumors. This case is an unusual example of histologically proven benign adrenal myelolipoma that was hypermetabolic on FDG-PET imaging. Correlation of pathologic and imaging findings demonstrated that the hypodense regions on CT were hypometabolic on FDG-PET and corresponded to cystic necrosis and adipose elements, whereas the adenomatous and hematopoietic elements were hypermetabolic.(Mol Imag Biol 2002;4:355–358) © 2002 Elsevier Science, Inc. All rights reserved. Key Words: Whole-body PET; FDG; Adrenal myelolipoma.
Introduction
Case Report
U
A 60-year-old white female presented with a history of non-specific lower mid-back pain with no prior history of malignancy. An MRI of the lumbar spine showed a large mass in the left retroperitoneum, confirmed by a CT of the abdomen. On CT, this 15-cm heterogeneous mass (Figure 1) contained cystic, solid, and adipose components that appeared to be arising within or adjacent to the left adrenal gland. Calcification was also present within the lesion. The patient had no symptoms of hormone excess or catecholamine hypersecretion. Portions of the mass were markedly hypermetabolic on 2-deoxy-2-[18F]fluoro-D-glucose positron emission tomography (FDG-PET) imaging (Figure 2) with several central areas of photopenia suggestive of malignancy with central necrosis. The surgically resected lesion revealed weighed 610 g and measured 15 x 13 x 10 cm. Macroscopic examination of the gross specimen (Figure 3) revealed a round, well-encapsulated soft tissue mass with a 3 0.5-cm rim of pale yellowish tissue along one aspect, a tan-reddish brown parenchyma with a prominent off-center area of red marrow mea-
nexpected adrenal lesions are often found on computerized tomography (CT) or magnetic resonance imaging (MRI) imaging performed for suspected abdominal disease. Most adrenal lesions are likely to be benign, even in patients with known primary extra-adrenal malignancy.1 Benign adenomas are the most common cause of nonfunctioning adrenal lesions. The incidence of adrenal myelolipoma at autopsy varies from 0.08–0.2%.2 Histologically, they are benign neoplasms composed of mature adipose tissue and hematopoietic elements.3–5 These benign adrenal lesions usually remain small and asymptomatic; however, they occasionally reach massive proportions and become symptomatic, resulting in non-specific complaints generally related to mechanical compression of adjacent organs.
Address correspondence to: Dr. Dominique Delbeke, Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, 21st Avenue South & Garland, Nashville, TN 37232-2675. Email: [email protected]
355
356 Molecular Imaging and Biology, Volume 4, Number 5
Figure 1. A CT scan of the abdomen demonstrated a 15-cm complex left adrenal mass containing soft tissue, cystic, and adipose components based on Houndsfield unit measurements.
suring about 7 cm in dimension, and cystic areas filled with yellow clear fluid. Microscopic examination (Figure 4) revealed that the lesion was arising from the adrenal cortex and had extensive adenomatous changes, including large cortical cells with abundant eosinophilic cytoplasm, large nuclei and prominent nucleoli indicating polyploidy. Foci of osseous metaplasia, adipose tissue with cystic necrosis and abundant hematopoietic elements were also identified. These findings were diagnostic of a benign adrenal myelolipoma. Correlation of the pathologic and imaging findings revealed that the hypodense regions on CT scan were hypometabolic on FDG-PET images and corresponded to cystic necrosis and adipose elements on the histologic section. The more dense regions on CT scan were
Figure 2. Transaxial (A) and coronal (B) FDG-PET images demonstrated a large hypermetabolic lesion with central regions of photopenia, usually indicative of a malignant tumor with central necrosis and/or hemorrhage. In this case, however, the hypermetabolism corresponded to the hematopoietic and adenomatous elements, while the hypometabolism corresponded to cystic necrosis and adipose elements.
hypermetabolic on FDG-PET images and represented the hematopoietic and adenomatous elements on the histologic section.
Discussion In this case, a 15-cm adrenal myelolipoma demonstrated areas of marked FDG uptake in a pattern suggestive of a metabolically active malignant neoplasm.
DG Uptake in Giant Adrenal Myelolipoma / Ludwig et al. 357
Figure 3. Photograph of the cut section of the left retroperitoneal mass shows a 15-cm well-encapsulated soft tissue mass with a 3 0.5-cm rim of adrenal tissue and focal cystic irregularities filled with yellow clear fluid. The yellowish-brown areas corresponded to adipose tissue, whereas the reddish regions were indicative of hematopoietic elements.
To our knowledge, the few reported cases of adrenal myelolipoma that have been imaged with FDG-PET have shown no significant FDG uptake.6 Adrenal myelolipoma is a benign neoplastic lesion composed of mature adipose tissue admixed with hematopoietic elements in various proportions. The age range of patients with adrenal myelolipoma is 17 to 93 years, with an average age at diagnosis of 50 years, it is rare in individuals under 30 years of age. Myelolipomas are usually non-secreting but have been associated with a variety of endocrine disturbances, including Cushing’s syndrome (combined with an adrenal cortical adenoma), pituitary-dependent Cushing’s disease, Addison’s disease, virilism, and pseudo-hermaphroditism. The color varies from pale yellow to deep red or reddish-brown depending upon the relative proportions of adipose and hematopoietic elements. Occasionally, infarct or hemorrhage occurs with secondary hematoma formation or fibrosis. Rarely, foci of ossification are seen, as in this case. On CT imaging, myelolipomas are usually well-circumscribed with a variable appearance depending upon the proportion of adipose tissue present. Lesions with little or no adipose tissue may be difficult to distinguish from other adrenal tumors. On MRI, the adipose components tend to have a typical bright appearance on T1-weighted images with signal drop-out on fat saturation sequences. Recently FDG-PET imaging has shown great potential in differentiating benign from malignant adrenal lesions with a sensitivity of 100%, specificity of 94%, and accuracy of 96%.6–8 In patients with known malignancy, FDG-PET has the additional potential of dem-
Figure 4. A whole mount histologic section illustrates the adenomatous elements (blue), adipose elements (white), and hematopoietic elements (red) of the tumor consistent with a benign adrenal myelolipoma.
onstrating unsuspected extra-adrenal and distant metastases.6 The most common benign and malignant tumors of the adrenal gland are adenomas and metastases, respectively. Benign adenomas are usually not FDG-avid, although occasional cases of hypermetabolic benign adrenal adenomas have been reported.7,8 Among the primary tumors that can arise from the adrenal gland, adrenal carcinomas are usually markedly FDG-avid. The degree of FDG uptake of neuroendocrine tumors is more variable and may be related to their degree of differentiation.9 Most malignant, and approximately 50% of benign pheochromocytomas accumulate FDG.10
Conclusion This case is an unusual example of histologically proven benign adrenal myelolipoma with extensive adenomatous changes and hematopoietic elements that were hypermetabolic on FDG-PET imaging.
References 1. Abrams, H.L.; Spiro, R.; Goldstein, N. Metastases in carcinoma: analysis of 1000 autopsied cases. Cancer 3:74–85; 1950. 2. Enzimer, F.M.; Sharen, W.W. Benign lipomatous tumors. In: Enzimer, F.M., Sharen, W.W., eds. Soft tissue tumors. 3rd ed. St. Louis:Mosby; 1995: pp 409–410. 3. Yildiz, L.; Akpolat, I.; Erzurumlu, K.; et al. Giant adrenal myelolipoma: case report and review of the literature. Pathol. Int. 50:502–504; 2000. 4. Vara Castrodeza, A.; Madrigal Rubiales, B.; Veiga Gonzalez, M.; et al. Adrenal gland myelolipoma: radiological review. Arch. Esp. Urol. 54:73–76; 2001.
358 Molecular Imaging and Biology, Volume 4, Number 5
5. O’Daniel-Pierce, M.E.; Weeks, J.A.; McGrath, P.C. Giant adrenal myelolipoma. South Med. J. 89:1116–1118; 1996. 6. Maurea, S.; Klain, M.; Mainolfi, C.; et al. The diagnostic role of radionuclide imaging in evaluation of patients with nonhypersecrating adrenal masses. J. Nucl. Med. 42: 884–892; 2001. 7. Yun, M.; Kim, W.; Alnafisi, N.; et al. 18F-FDG PET in characterizing adrenal lesions detected on CT or MRI. J. Nucl. Med. 42:1795–1799; 2001. 8. Erasmus, J.J.; Patz, E.F. Jr; McAdams, H.P.; et al. Evalua-
tion of adrenal masses in patients with bronchogenic carcinoma using 18F-fluorodeoxyglucose positron emission tomography. AJR 168:1357–1360; 1997. 9. Erasmus, J.J.; McAdams, H.P.; Patz, E.F.; et al. Evaluation of primary pulmonary carcinoid tumors using FDG PET. AJR 170:1369–1373; 1998. 10. Shulkin, B.L.; Thompson, N.W.; Shapiro, B.; et al. Pheochromocytomas: imaging with 2-[fluorine-18]fluoro-2deoxy-D-glucose PET. Radiology. 212:35–41; 1999.