A recurrent homozygous LMNA missense variant p.Thr528Met causes atypical progeroid syndrome characterized by mandibuloacral dysostosis, severe muscular dystrophy, and skeletal deformities

Atypical progeroid syndromes (APS) are premature aging syndromes caused by pathogenic LMNA missense variants, associated with unaltered expression levels of lamins A and C, without accumulation of wild-type or deleted prelamin A isoforms, as observed in Hutchinson-Gilford progeria syndrome (HGPS) or HGPS-like syndromes. A specific LMNA missense variant, (p.Thr528Met), was previously identified in a compound heterozygous state in patients affected by APS and severe familial partial lipodystrophy, whereas heterozygosity was recently identified in patients affected by Type 2 familial partial lipodystrophy. Here, we report four unrelated boys harboring homozygosity for the p.Thr528Met, variant who presented with strikingly homogeneous APS clinical features, including osteolysis of mandibles, distal clavicles and phalanges, congenital muscular dystrophy with elevated creatine kinase levels, and major skeletal deformities. Immunofluorescence analyses of patient-derived primary fibroblasts showed a high percentage of dysmorphic nuclei with nuclear blebs and typical honeycomb patterns devoid of lamin B1. Interestingly, in some protrusions emerin or LAP2α formed aberrant aggregates, suggesting pathophysiology-associated clues. These four cases further confirm that a specific LMNA variant can lead to the development of strikingly homogeneous clinical phenotypes, in these particular cases a premature aging phenotype with major musculoskeletal involvement linked to the homozygous p.Thr528Met variant.

Concomitant Paravertebral FDG Uptake Helps Differentiate Supraclavicular and Suprarenal Brown Fat Uptake From Malignant Uptake When CT Coregistration Is Not Available

OBJECTIVES

Fluorine-18 fluorodeoxyglucose (F-18 FDG) uptake in brown adipose tissue (BAT) in the supraclavicular, superior mediastinal, paravertebral, and suprarenal/perinephric regions has been recognized. Of these 4 areas, uptake in the supraclavicular, mediastinal, and suprarenal areas may be difficult to differentiate from malignancy for those who interpret PET images only without CT coregistration or fusion. We assessed the prevalence and concomitance of F-18 FDG uptake in these 4 BAT regions.

METHODS

A total of 1495 F-18-FDG PET studies were reviewed. Distinct patterns compatible with BAT uptake in the 4 regions were graded and correlated with each other.

RESULTS

Of the 1495 studies, supraclavicular uptake was seen in 40 (2.7%), paravertebral uptake in 29 (1.9%), mediastinal uptake in 23(1.5%), and suprarenal uptake in 11 (0.7%). Of the 40 studies showing supraclavicular uptake, paravertebral uptake was also seen in 27 (68%), mediastinal uptake in 23 (58%), and suprarenal uptake in 11 (28%). Alternatively, of the 29 studies showing paravertebral uptake, all but 2 studies (93%) also had concomitant supraclavicular uptake. No studies showed isolated mediastinal or suprarenal uptake. All studies with mediastinal uptake also had supraclavicular uptake, and all studies with suprarenal uptake also had paravertebral uptake.

CONCLUSIONS

Virtually all of mediastinal and suprarenal BAT uptake was associated with supraclavicular and paravertebral uptake, respectively. Nearly all paravertebral uptake coexisted with supraclavicular uptake. Even when CT coregistration is not available, concomitant paravertebral uptake can help differentiate suprarenal uptake and somewhat less typical supraclavicular BAT uptake from malignant uptake, and concomitant supraclavicular uptake can help differentiate mediastinal uptake from malignant uptake.

Uptake in supraclavicular area fat ("USA-Fat"): description on 18F-FDG PET/CT

The supraclavicular region is a common site for lymph node metastases. A commonly reported type of nonmalignant (18)F-FDG uptake on PET imaging in the supraclavicular region is "muscle uptake" purportedly due to muscle contraction in tense patients during the (18)F-FDG uptake phase. PET/CT offers the unique opportunity to correlate PET findings with CT anatomy in the supraclavicular region.

METHODS

Images from the first 359 consecutive clinical whole-body studies (in 347 patients) using (18)F-FDG and a PET/CT scanner (with CT attenuation correction and ordered-subsets expectation maximization [OSEM] reconstruction) were retrospectively reviewed. The supraclavicular region was evaluated for the presence of abnormal uptake on PET images, and the corresponding CT findings were assessed. Three distinct patterns of abnormal (18)F-FDG uptake were noted: pattern A (uptake localizing to supraclavicular area fat [USA-fat], i.e., without corresponding lymph node or muscle uptake on CT), pattern B (uptake localizing to muscle on CT), and pattern C (uptake localizing to lymph nodes or soft-tissue masses on CT).

RESULTS

Forty-nine patients (14.1%) (32 female, 17 male; mean age, 51.4 +/- 15.6 y; age range, 12-77 y) showed abnormal (18)F-FDG uptake in the supraclavicular region. Twenty patients (5.8%) had muscle uptake (group B); 15 (4.3%) had definite abnormal lymph nodes (group C). However, 14 patients (4.0%) had USA-fat (group A) and foci of very low Hounsfield units on CT. These foci were also present on (68)Ge attenuation-corrected images (when obtained) and non-attenuation-corrected images. Uptake in USA-fat was typically bilateral and symmetric, intense, more often multifocal than linear, and located in fat on PET/CT. Age was not significantly different for group C versus the 2 other groups. Intensity; mean standardized uptake value, lean (SUV(L MEAN)); or maximum standardized uptake value, lean (SUV(L MAX)), did not allow differentiation between patterns A and C (P > 0.05). Standardized uptake values (SUV(L MAX), 3.1; SUV(L MEAN), 2.1) were significantly lower in group B than in the 2 other groups (P < 0.005).

CONCLUSION

So-called muscle uptake in the supraclavicular region may be caused in a significant proportion of cases by an unrelated process we call the USA-fat finding, with (18)F-FDG uptake in tissues of low-Hounsfield (fat) density. This finding most likely reflects an underlying nonpathologic process that we hypothesize to be in foci of brown fat. This intense supraclavicular uptake should be recognized and should not be misinterpreted as a malignant metastatic process or as muscle uptake.

Restricted infraclavicular distribution of the local anesthetic solution after infraclavicular brachial plexus block

BACKGROUND AND OBJECTIVES

The distribution of local anesthetic after different approaches for brachial plexus anesthesia could be responsible for the varying rates of side effects, such as phrenic block, hoarseness, and Horner's syndrome associated with each approach. We compared the distribution of local anesthetic within the neurovascular space in infraclavicular block with that of interscalene and supraclavicular block.

METHODS

In a prospective analysis using fluoroscopy, we studied the distribution of a solution of local anesthetic containing radiologic contrast medium in 18 patients. Six patients received an interscalene block, another 6 patients received a perpendicular supraclavicular block, and another 6 patients, a perpendicular coracoid block.

RESULTS

Distribution of the anesthetic solution in the interscalene and supraclavicular groups extended to both supraclavicular and infraclavicular spaces in all patients. This distribution was significantly different (P <.05) compared with that of the infraclavicular group. In this group, the solution remained below the clavicle in every patient.

CONCLUSIONS

Spread of the local anesthetic from the infraclavicular space after infraclavicular coracoid block appears to be limited to below the level of the clavicle. Conversely, local anesthetic solution passes below the clavicle in all patients given interscalene or supraclavicular blocks.

Upper clavicular and cardiac meta-[123I]iodobenzylguanidine uptake in children

In order to clarify some of the particularities and pitfalls of the MIBG thoracic scan, we report our experience with 5 children with Stage III or IV neuroblastoma who presented equivocal scans. The physiological thoracic distribution of MIBG in children differs from that in adults and has to be taken in account in the accurate interpretation of the scans.

Changes in cortical thickness of the clavicle and serum bone gamma-carboxyglutamic acid-containing protein in the elderly in an island community in western Japan

The cortical thickness of the clavicle (CTC), concentrations of bone gamma-carboxyglutamic acid-containing (Gla) protein (s-BGP, osteocalcin), alkaline phosphatase (s-ALP), calcium (s-Ca) and inorganic phosphorus (s-P) in serum, and calcium/creatinine (u-Ca/Cr) and inorganic phosphorus/creatinine (u-P/Cr) ratios in urine were examined in 211 subjects aged over 40 years in Oshima Island in Nagasaki prefecture. CTC decreased and s-BGP increased with age in both sexes, especially in women. Serum BGP was significantly higher in women than in men at the ages of 50's and over. Serum ALP in women increased until the ages of 60's. Serum Ca at the ages of 50's and s-P at the ages of 60's and over were higher in women than in men. As the increase in s-BGP is reported to be coincident with active bone formation, our findings do not support the view that age-related bone loss, especially in women, primarily results from decrease in bone formation.