Rothmund-Thomson Syndrome

Rothmund-Thomson syndrome (poikiloderma congenitale) is a rare autosomal recessive disorder that presents in infancy with skeletal issues (see below), skin rash (poikiloderma), partial or total alopecia, eye issues (photophobia, cataract, microphthalmia, microcornea, strabismus, and glaucoma), and hormonal issues (hypogonadism, growth hormone deficiency). The patients are also predisposed to developing osteosarcoma and basal and squamous cell carcinoma of the skin.

Skeletal problems that can be seen on radiographs include mineralization disorders (osteoporosis or osteosclerosis), radial hypoplasia or agenesis, absent thumb, mild epiphysial dysostosis and metaphyseal sclerosis, knee subluxation, and flattened and elongated vertebral bodies.

References

• Gelaw B, Ali S, Becker J. Rothmund-Thomson syndrome, Klippel-Feil syndrome, and osteosarcoma. Skeletal Radiol. 2004 Oct;33(10):613-5.
• Mehollin-Ray AR, Kozinetz CA, Schlesinger AE, Guillerman RP, Wang LL. Radiographic abnormalities in Rothmund-Thomson syndrome and genotype-phenotype correlation with RECQL4 mutation status. AJR Am J Roentgenol. 2008 Aug;191(2):W62-6.

Focal Nodular Hyperplasia on F-18 FDG-PET

Focal nodular hyperplasia (FNH) characteristically has FDG avidity similar to (more common) or lower than the surrounding liver. In rare circumstances, FNH can present as a hypermetabolic lesion, creating some confusion.

The case above shows the typical appearance of focal nodular hyperplasia on CT. FDG-PET shows that the uptake of the lesion (arrow) is similar to the adjacent liver.

Differential considerations on FDG-PET include adenoma, hemangioma, and hepatocellular carcinoma.

References

• Aznar DL, Ojeda R, Garcia EU, Aparici F, Sánchez PA, Flores D, Martínez C, Sopena R. Focal nodular hyperplasia (FNH): a potential cause of false-positive positron emission tomography. Clin Nucl Med. 2005 Sep;30(9):636-7.
• Kurtaran A, Becherer A, Pfeffel F, Müller C, Traub T, Schmaljohann J, Kaserer K, Raderer M, Schima W, Dudczak R, Kletter K, Virgolini I. 18F-fluorodeoxyglucose (FDG)-PET features of focal nodular hyperplasia (FNH) of the liver. Liver. 2000 Dec;20(6):487-90.

Focal Pure Ground-Glass Opacities in the Setting of Primary Lung Carcinoma

A focal pure ground-glass opacity (GGO) is defined on HRCT as an area of homogeneously increased opacity of the lung without a solid component and with preservation of the underlying bronchial and vascular margins.

One or more of these focal pure ground-glass opacities are often seen in the lungs, sometimes in more than one lobe, in addition to the primary lung cancer. These can represent neoplastic lesions (e.g., atypical adenomatous hyperplasia, bronchioloalveolar carcinoma, lymphoma, and even metastases) or inflammatory lesions and fibrosis.

Most focal pure ground-glass opacities associated with lung cancer do not change in size during follow-up. In addition, the prognosis of patients with a primary lung cancer and coexisting atypical adenomatous hyperplasia or bronchoalveolar carcinoma is related more to the primary lung cancer than the atypical adenomatous hyperplasia or bronchoalveolar carcinoma. Therefore, it has been suggested that therapy be directed at resection of the primary tumor without intervention in the remaining focal pure ground-glass opacities.

The case above is from a patient with a resected primary lung carcinoma and with multiple focal pure ground-glass opacities (pink arrows). These had not changed in size over a 4-year period. A more solid lesion (blue arrow) had mild FDG avidity (not shown) and had grown slightly in the same interval.

References

Tsutsui S, Ashizawa K, Minami K, Tagawa T, Nagayasu T, Hayashi T, Uetani M. Multiple focal pure ground-glass opacities on high-resolution CT images: Clinical significance in patients with lung cancer. AJR Am J Roentgenol. 2010 Aug;195(2):W131-8.

Cystic Lymph Nodes in Head and Neck Squamous Cell Carcinomas

Cystic cervical nodal metastases are specific and easily recognizable manifestation of a subset of head and neck squamous cell carcinomas (SCC) arising from the Waldeyer ring and associated with human papillomavirus (HPV).

Cystic lymph nodes can be seen in as many as 50% of squamous cell carcinomas arising from the Waldeyer ring, and about 50% of all tonsil/base of tongue squamous cell carcinomas are positive for human papillomavirus. These cystic nodal metastases are typically located in the jugulodigastric region and can be moderately large and associated with relatively small or occult primary tumors.

The cyst formation in these lymph nodes is thought to be due to spontaneous degradation of keratin and cellular debris inside the lymph node or formation of a true epithelium-lined cyst in the center of the lymph node. It is not thought to be due to central necrosis as can be seen in cystic nodal metastases elsewhere.

Other head and neck cancers, notably papillary thyroid carcinoma, can result in cystic lymph node metastasis. Carcinoma arising in a branchial cleft cyst is now considered to be exceedingly rare. Indeed, many lesions previously diagnosed as branchial cleft carcinomas are now thought to have represented cystic metastasis from a tonsillar primary squamous cell carcinoma.

References

Goldenberg D, Begum S, Westra WH, Khan Z, Sciubba J, Pai SI, Califano JA, Tufano RP, Koch WM. Cystic lymph node metastasis in patients with head and neck cancer: An HPV-associated phenomenon. Head Neck. 2008 Jul;30(7):898-903.

F18-FDG PET and Hepatocellular Carcinoma

FDG-PET is relatively insensitive for hepatocellular carcinoma. Well-differentiated tumors can have metabolic activity that can be similar to the normal liver parenchyma, resulting in reported sensitivities of at most ~65%. The sensitivity falls to 0% in patients with end-stage liver disease awaiting transplantation.

However, there may be a role for FDG-PET in prognosis, with FDG-avid lesions representing poorly differentiated tumors and poorer prognosis.

The image above shows extensive hepatocellular carcinoma in the liver with a right adrenal metastasis (arrows). The FDG uptake pattern is essentially normal in both the liver and the right adrenal gland.

References

• Ahn SG, Kim SH, Jeon TJ, Cho HJ, Choi SB, Yun MJ, Lee JD, Kim KSJ. The role of preoperative [18F]fluorodeoxyglucose positron emission tomography in predicting early recurrence after curative resection of hepatocellular carcinomas. Gastrointest Surg. 2011 Nov;15(11):2044-52. Epub 2011 Sep 9.
• Hustinx R. PET imaging in assessing gastrointestinal tumors. Radiol Clin North Am. 2004 Nov;42(6):1123-39, ix.

Role of Radiography in Diagnosis of Rheumatoid Arthritis

The most recent guidelines by the American College of Rheumatology and European League Against Rheumatism have dropped radiography from their diagnostic criteria and instead rely on physical examination findings and laboratory data.

The reason for this change is that modern therapy relies on early diagnosis and treatment with disease-modifying antirheumatic drugs (DMARDs), and radiographs are painfully insensitive in this setting (~70% of patients with early disease have normal radiographs).

MRI or ultrasound are much more sensitive, but the guidelines limit their use to confirmation of the clinical findings after clinical classification of a patient.

Radiography still has a role in excluding other joint diseases (e.g., osteoarthritis) and to assess joint damage in established cases of rheumatoid arthritis.

References

• Aletaha D, Neogi T, Silman AJ, et al. 2010 rheumatoid arthritis classification criteria: an American College of Rheumatology/European League Against Rheumatism collaborative initiative. Ann Rheum Dis. 2010 Sep;69(9):1580-8. Erratum in: Ann Rheum Dis. 2010 Oct;69(10):1892.
• Rowbotham EL, Grainger AJ. Rheumatoid arthritis: ultrasound versus MRI. AJR Am J Roentgenol. 2011 Sep;197(3):541-6.
• Tan YK, Conaghan PG. Imaging in rheumatoid arthritis. Best Pract Res Clin Rheumatol. 2011 Aug;25(4):569-84.

FDG and Lactating Women

Lactating women have increased uptake in the breast(s) used for breastfeeding. For example, a breast that is consistently refused by baby or breasts in non-breastfeeding women, do not have significantly increased uptake.

No significant radiotracer is excreted in the breast milk, and the radiation dose received by the baby is more from close contact with the breast than from ingestion of radioactive milk.

References

Hicks RJ, Binns D, Stabin MG. Pattern of uptake and excretion of (18)F-FDG in the lactating breast. J Nucl Med. 2001 Aug;42(8):1238-42.