Rib Interspace Research Articles

Optimizing Lung Ultrasound: The Effect of Depth, Gain and Focal Position on Sonographic B-Lines.

Ultrasonographic B-lines are artifacts present in alveolar-interstitial syndromes. We prospectively investigated optimal depth, gain, focal position and transducer type for B-line visualization and image quality. B-Lines were assessed at a single rib interspace with curvilinear and linear transducers. Video clips were acquired by changing parameters: depth (6, 12, 18 and 24 cm for curvilinear transducer, 4 and 8 cm for linear transducer), gain (10%, 50% and 90%) and focal position (at the pleural line or half the scanning depth). Clips were scored for B-lines and image quality. Five hundred sixteen clips were obtained and analyzed. The curvilinear transducer improved B-line visualization (63% vs. 37%, p < 0.0001), with higher image quality (3.52 ± 0.71 vs. 3.31 ± 0.86, p=0.0047) compared with the linear transducer. B-Lines were better visualized at higher gains (curvilinear: gain of 50% vs. 10%, odds ratio=7.04, 95% confidence interval: 4.03-12.3; gain of 90% vs. 10%, odds ratio=9.48, 95% confidence interval: 5.28-17.0) and with the focal point at the pleural line (odds ratio=1.64, 95% confidence interval: 1.02-2.63). Image quality was highest at 50% gain (p=0.02) but decreased at 90% gain (p < 0.0001) and with the focal point at the pleural line (p < 0.0001). Image quality was highest at depths of 12-18 cm. B-Lines are best visualized using a curvilinear transducer with at least 50% gain and focal position at the pleural line. Gain less than 90% and image depth between 12 and 18 cm improve image quality.

Intradialytic Hypotension in Critically Ill Patients on Hemodialysis With A-Line versus B-Line Pattern on Lung Ultrasonography

Intradialytic Hypotension in Critically Ill Patients on Hemodialysis With A-Line versus B-Line Pattern on Lung Ultrasonography

Avoiding the Internal Mammary Artery During Parasternal Blocks: Ultrasound Identification and Technique Considerations

Fascial plane chest wall blocks are an integral component to optimal multimodal postoperative analgesia in breast and cardiothoracic surgery, facilitating faster functional recovery and earlier discharge. Pectoral nerves block and serratus plane block have been used to treat postsurgical pain after breast and cardiothoracic surgeries; however, they cannot be used to anesthetize the anterior chest wall. Ultrasound parasternal block, or pectointercostal fascial block and transversus thoracis muscle plane block are two novel ultrasound-guided anesthetic and analgesic techniques that block the anterior cutaneous branches T2 to T6 intercostal nerves, providing anesthesia and analgesia to the anterior chest wall. Ultrasound parasternal block/pectointercostal fascial block and transversus thoracis muscle plane block are performed in the region of the internal mammary artery and could be considered to treat post-thoracotomy pain. This anatomic region is innervated by the anterior cutaneous branches T2-to-T6 intercostal nerves, which are obliterated during cardiac surgery artery harvesting. At the level of the fourth parasternal rib interspace, the internal mammary artery can be identified between the internal intercostal muscle and transversus thoracis muscle as a longitudinal pulsatile structure approximately 1.5 cm from the lateral border of the sternum. The transversus thoracis muscle is variable in many people and, thus, is an unreliable target and is difficult to visualize with ultrasound. Moreover, patients with a history of coronary artery bypass grafting could have tissue disruption in the transversus thoracis plane because of the internal mammary artery harvest, making transversus thoracis muscle identification more difficult. Despite ultrasound parasternal block and transversus thoracis muscle plane block having good safety profiles and reduced risk of complications, pneumothorax, local anesthetic systemic toxicity, and internal mammary artery injury or hematoma should be considered. If the block is performed before cardiac surgery, both the right and left internal mammary arteries could be damaged. The injury could render the internal mammary artery unusable for bypass grafting. If the block is performed after left internal mammary artery harvesting at the end of coronary artery bypass grafting, only the right internal mammary artery could be damaged. In patients in whom the internal mammary artery has been surgically used and the transversus thoracis muscle is difficult to visualize, ultrasound parasternal block should be considered. In patients in whom the internal mammary artery could be difficult to visualize or considering that it is in the vicinity of the transversus thoracis muscle plane block target and that the transversus thoracis muscle is difficult to visualize with ultrasound after internal mammary artery harvesting, then ultrasound parasternal block should be considered. The authors believe that ultrasound parasternal block is the safer regional technique for protecting the internal mammary artery and the pleura because it is more superficial. For this reason, ultrasound parasternal block also could be performed by inexperienced anesthesiologists. Although ultrasound parasternal block is more superficial, its superiority in terms of safety is yet to be proven. Additional studies are warranted to validate the authors' hypothesis.

Internal mammary artery perforator (IMAP) flaps

Oncologic defects of the head and neck require a detailed understanding of regional anatomy to optimize and simplify reconstruction. While free tissue transfer has become the standard bearer for most soft tissue defects, local flaps still remain a high-quality, reliable option. The internal mammary vasculature provides predictable perforators to the chest wall skin that can be transposed to lower neck wounds. Paired arteries and veins perforate through the second and third rib interspaces to perfuse skin overlying the parasternal and infraclavicular areas. Donor site morbidity is minimal with primary closure performed in most occasions. This flap is ideal for smaller esophageal fistulae, paratracheal wounds, and neck incisional dehiscence.

AIUM Practice Parameter for the Performance of Point-of-Care Ultrasound Examinations.

AIUM Practice Parameter for the Performance of Point-of-Care Ultrasound Examinations.

The intercostal nerve as a target for diagnostic biopsy.

OBJECTIVE Peripheral nerve biopsy is a useful tool in diagnosing peripheral neuropathies. Sural and gracilis nerves have become the most common targets for nerve biopsy. However, the yield of sural nerve biopsy is limited in patients who have motor neuropathies, and gracilis nerve biopsy presents technical challenges and increased complications. The authors propose the intercostal nerve as an alternative motor nerve target for biopsy. METHODS A total of 4 patients with suspected peripheral neuropathies underwent intercostal nerve biopsy at the authors' institution. A rib interspace that is inferior to the pectoralis muscle and anterior to the anterior axillary line is selected for the procedure. Generally the lower intercostal nerves (i.e., T7-11) are targeted. An incision is made over the inferior aspect of the superior rib at the chosen interspace. Blunt dissection is carried down to the neurovascular bundle and the nerve is isolated, ligated, and cut to send for pathological examination. RESULTS The average operative time for all cases was 73 minutes, with average blood loss of 8 ml. Biopsy results from 1 patient exhibited axonopathy, and the other 3 patients demonstrated axonopathy with demyelination. There were no short- or long-term postoperative complications. None of the patients reported sensory or motor deficits related to the biopsy at 6 weeks postoperatively. CONCLUSIONS The intercostal nerve can be an alternative target for biopsy, especially in patients with predominantly motor neuropathies, due to its mixed sensory and motor fibers, straightforward anatomy, minimal risk of serious sensory deficits, and no risk of motor impairment.

Molluscan marginalia: hidden morphological diversity at the bivalve shell edge

Molluscan shells exhibit a high and largely neglected diversity of serrations and crenulations at the growing margin. A survey of living and Cenozoic fossil bivalves indicates that serrations, in which the external ribs or interspaces between ribs extend radially beyond the general contour of the valve margin, may be symmetrical or asymmetrical. Projections whose adumbonal edge more nearly parallels the shell edge than the abumbonal edge occur on the posterior valve margins of many limids, cardiids and donacids, as well as in the arcid Anadara and a few concentrically ridged tellinids. In many cardiids, posterior serrations form as extensions of ribs, whereas ventral and anterior projections are extensions of rib interspaces. Asymmetrical serrations are almost always found on shell edges that are polished, indicating that the mantle extends slightly over the valve margin to the outside. I tentatively suggest that asymmetrical serrations enable the valves to close around siphons or other mantle extensions without injuring these soft tissues, so that the bivalve can maintain sensory contact with the environment even while the shell is shut. A preliminary comparison with brachiopods indicates that the diversity of conditions at the shell edge is much higher in bivalves. Together with the largely warm-water and marine distribution of marginal modifications in bivalves, these comparisons reflect the higher metabolic potentials of bivalves relative to brachiopods, and show that the shell edge is a rich source of evidence about function and mode of life in fossils.

Retrospective Computed Tomography Mapping of Intrapleural Air May Demonstrate Optimal Window for Ultrasound Diagnosis of Pneumothorax

When a pneumothorax exists, free air should rise to the most nondependent region within the chest. Current ultrasound (US) examination methodologies may exclude visualization of these areas that may limit the sensitivity of the examination. This retrospective study uses computed tomography (CT) scans to precisely evaluate where free air within the thorax occurs and correlates this location with a presumably optimal US interrogation window. A total of 94 CT scans of patients with a pneumothorax in a single institution from December 2006 to January 2010 were examined. The borders and volumes of each pneumothorax were precisely measured by a radiologist. Logistic regression was used to determine the relationship between volume and location of intrapleural air at specified areas of the hemithorax. Sensitivities relating location of intrapleural air at a specific landmark and side of thorax were calculated. All but 3 of the pneumothoraces extended to the sternum. In all, 83 patients demonstrated a pneumothorax between rib interspaces 3 and 6 (mean pneumothorax volume 300.4 mL, 95% confidence interval [CI] 217.4-383.3), and 11 patients did not (mean pneumothorax volume 4.5 mL, 95% CI 1.7-7.3; P < .0001). The cumulative sensitivity for the presence of intrapleural air at rib interspaces 3 to 6 along the sternal border was 88%. This was consistent regardless of the side of hemithorax (right 91% and left 86%). The CT scans demonstrate that intrapleural air most often collects along the mediastinum between ribs 3 and 6 on either side of the chest. Although no USs were performed in this retrospective study, one may infer that a parasternal approach along rib interspaces 3 to 6 is an easy and sensitive window to diagnose pneumothorax with US.

Beyond Belief

Beyond Belief

Noninvasive assessment of liver fibrosis

Noninvasive assessment of liver fibrosis

Tips for Successful Microvascular Abdominal Flap Breast Reconstruction Utilizing the “Total Rib Preservation” Technique for Internal Mammary Vessel Exposure

The internal mammary vessels (IMVs) are increasingly the recipients for free flap breast reconstruction (FFBR). Access traditionally entails removing a segment of the third costal cartilage. Despite excellent exposure, some authors have reported localized tenderness as well as a thoracic contour deformity. We introduced the "total rib preservation" technique for IMV exposure after specific request by a patient, and have used it for all subsequent reconstructions. All patients who underwent FFBR with rib preservation by a single surgeon in the year beginning June 2008 were studied prospectively. Intraoperative measurements of the inter-rib space available for microvascular anastomosis were taken. Operative details and flap outcomes were compared with a cohort of earlier patients who underwent rib sacrifice. Over a 12-month period, 42 FFBRs in 37 patients (36 deep inferior epigastric perforator, five muscle-sparing transverse rectus abdominis myocutaneous, and one superficial inferior epigastric artery flap) were performed by a single operator. All flap transfers were successful. In the first 4 patients, the interspace between the third and fourth ribs was used; but for all subsequent patients the second and third rib interspace was used. The average distance between adjacent ribs was 21.3 mm (range, 9-28 mm) and the vessel preparation time decreased from an average of 93 to 49 minutes (first and last 5 cases). There was no significant difference in mean ischemia time between the rib preservation and the rib sacrifice groups (104.4 vs. 103.6 minutes). The total rib preservation method of IMV exposure is a viable, reproducible, and reliable option for microvascular breast reconstruction. It does not increase warm ischemia, which suggests time taken for anastomosis is not affected by rib preservation. There is a learning curve and care has to be taken to avoid possible pitfalls. We recommend the use of a higher rib interspace than originally described because of the greater vessel calibre, superior vessel exposure, and therefore, easier anastomosis.

The Rib-Sparing Technique for Internal Mammary Vessel Exposure in Microsurgical Breast Reconstruction

The internal mammary vessels are frequently used for free flap breast reconstruction and are typically dissected via resection of an entire rib cartilage. Resection of rib cartilage may cause increased postoperative pain or a depressed thoracic contour deformity. We have used a new, less invasive technique that does not resect rib cartilage and exposes the vessels within the rib interspace. Over a 3-year period, all breast free flaps performed with the rib-sparing technique were reviewed and compared with a group of flaps performed with the standard rib resection technique. The rib-sparing technique was performed for 74 flaps, with no significant increase in complications, including revision of anastomosis (3%), fat necrosis (11%), or flap loss (1%), when compared with a group of 125 flaps undergoing rib resection. This less invasive technique is reviewed in detail and may prove beneficial in regard to postoperative pain and incidence of chest wall deformities.

“Opened Book Technique for Accessing the Internal Mammary Vessels for Microanastomosis

The internal mammary (IM) vessels have been shown to be an excellent option for use as recipient vessels in microsurgical free tissue transfer. The authors preferentially use the IM vessels for all free flap breast reconstructions unless the IM perforators are suitable. Accessing the IM vessels in the past has involved the removal of an entire rib cartilage. Removal of an entire rib cartilage may be associated with increased postoperative pain, and a visible depression in the upper chest. In order to avoid these problems, they developed a method of accessing the IM vessels within the rib interspace, which does not require the removal of rib cartilage, is relatively bloodless, very reproducible, and can be performed under loupe magnification during the harvest of the free flap. The details of this procedure, which the authors call the “opened book” technique, were described in this report.

CT-scan based localization of the internal mammary chain and supra clavicular nodes for breast cancer radiation therapy planning

Background and purpose To evaluate the influence of the position and the exact localizations of supra clavicular nodes (SCN) and internal mammary chain (IMC) and their variability among patients in order to improve treatment planning in breast cancer (BC) patients. Patients and methods A total of 46 CT scans of the chest were examined. All patients were female treated with breast conserving surgery and radiotherapy. The study was divided into two phases. The first consisted of measurements on 20 diagnostic CT scans, performed in the supine position with both arms over the head. All patients received contrast. This first phase was performed as a training program for radiologist and radiation oncologist to prepare for the second phase of the study: 26 CT scans in treatment position on angled board without injection. For this second group, patients had one arm raised above the head (treated side) and the other kept by the side (contralateral side). Measurements were performed on both sides to evaluate the influence of the arm position. The depths of IM- and SC vessels were measured at five points: (1) the origin of the internal mammary artery, (2) the sterno-clavicular articulation, (3–5) the first, second and third rib interspaces (RI). Measurements of the depth and of the distance between the internal mammary vessels and the middle axis of the sternum were obtained using electronic calipers on a PACS workstation. Results There were important individual variations of the depth of SCN, as follows: 20–84 mm (diagnostic) and 19–64 (treatment position). No differences in the depth of the IMC were found between treated and contralateral side at the region of the I, II, and III rib interspaces. The lateral margin of the IMC was never more than 40 mm from the middle axis of the sternum (I, II, III rib interspaces). There was no difference in the lateral limits of IMC (the distance between the IM vessels and the middle axis of the sternum) between the two sides: treated and contralateral. Conclusions This study shows the importance of the patients' individual anatomy, their position and the large variability in the depth of SCN. It is important to visualize these regions to permit individual dosimetric optimization.

Fluoroscopically guided scapulothoracic injections.

After informed consent was obtained from the patient, the patient was placed in a prone oblique position on the fluoroscopy table of a C -arm system (Angioskop D 33, Siemens Medical Systems, Erlangen, Germany). The patient was asked to place the arm of the painful side either above the head or at the side of the body to move the scapula away from the chest wall. The choice of arm position depended on which one was more comfortable for the patient and which one best opened the tender area between the scapula and the ribs. The C -arm was rotated until the scapula and the scapulothoracic space were seen in profile. In most patients, the fluoroscopy tube was angled cephalocaudally to profile the anterior and posterior portions of the rib of interest in the same plane, which produced a lordotic view of the ribs. This view helped prevent inadvertent needle puncture of the rib interspace. The patient was asked where the pain was centered while the radiologist palpated medial and deep in relation to the scapula. The site of maximal tenderness was chosen for the

CT-targeted irradiation of the breast and internal mammary lymph nodes using a 5-field technique

Purpose: To develop an effective and resource-efficient radiotherapy technique to treat the breast and regional nodes, including the ipsilateral internal mammary nodes. Methods and Materials: Eighty female patients who underwent MRI scans for a variety of indications had coronal, T1-weighted images of the chest performed to determine the position of the internal mammary chain (IMC). Based on these results, a 5-field treatment technique was developed that would include the breast, supraclavicular fossa, and ipsilateral IMC, while maintaining a low dose to the heart, lungs, and contralateral breast. This technique was implemented in a cohort of 13 patients. Results: The lateral position of the right and left IMC were measured in three cephalo-caudad positions: at the clavicular heads, upper manubrium, and midsternum (at the 2nd/3rd rib interspace). The mean lateral separation between the right and left IMC chains at each level (and 95% confidence interval) at each level were 5.8 cm (4.67–7.00), 5.6 cm (4.49–6.73), and 5.9 cm (4.66–7.19), respectively. Treatment was delivered to 13 patients using a 5-field technique, with tangential photon fields for the breast, anterior and posterior supraclavicular/axillary field, and a matching anterior electron field. Three-dimensional treatment planning of a representative case confirmed adequate coverage of the planning target volume (PTV). The median dose to the whole heart was 10 Gy, and 20% of the ipsilateral lung received more than 20 Gy. Seven of the 13 patients treated experienced moist desquamation at the junction of the electron field and breast tangents, and 1 patient had persistent ulceration at 3 months’ follow-up. Conclusion: The 5-field technique described in this paper provides good coverage to the breast and regional nodes with acceptable toxicity, and without requiring three-dimensional treatment planning or intensity-modulated radiotherapy techniques.

Parasternal sonography of the internal mammary lymphatics in breast cancer: CT correlation

The purpose of this study was to evaluate the efficacy of parasternal ultrasonography (US) in diagnosing internal mammary lymph node metastases in breast cancer, an important site of occult metastases, adversely affecting the disease-free interval and long-term survival. Thirty-five patients who were diagnosed with breast cancer were examined for internal mammarian lymph node (IMLN) involvement with parasternal US, and results were correlated with computed tomography (CT). Longitudinal and transverse images of the first through sixth parasternal rib interspaces were evaluated with a 7.5-MHz linear-array transducer. The enlarged nodes were demonstrated as discrete, spherical or ovoid hypoechoic lesions in six cases with parasternal US, and corresponding CT scans confirmed the presence of lymphadenopathy. Our results suggest that parasternal US may be helpful in the evaluation of IMLN metastases in breast cancer as a part of staging the disease.

Fusion of radial ribs in Cardiidae (Bivalvia: Veneroida): implications for phylogenetic reconstruction and the study of iterative homology

To properly reconstruct the phylogeny of a taxon, it is necessary to determine homologies among taxa. The assumption that repeated structures are iterative homologues has resulted in phylogenetic confusion. Radial ribs have long been used as important taxonomic characters in bivalves, but a cladistic analysis of the Cardiidae has shown that radial ribs are not homologous across genera.Pre-Aptian cardiids have either simple, unornamented ribs, or have lost the ribs entirely. The genus Granocardium originates in the Aptian and has large spines on every third or fourth rib interspace. This row of spines is connected by a raised striation. The interspace bearing these spines is raised relative to other interspaces. Criocardium, a subgenus of Granocardium, originates in the Upper Cretaceous and has rows of small spines, also connected by a raised striation, on the interspaces not occupied by large spines; these interspaces are not concomitantly raised.When the character states of the large and small spines, their respective striations, ribs and interspaces are analyzed throughout the Cardiidae, it becomes apparent that adjacent pairs of ribs have fused independently on three occasions. In Cenozoic cardiids, the large spines and their striations are not between ribs but on top of them. On many taxa, the top of the rib is concave, reflecting the rib top's homology with the rib interspace of Granocardium. Furthermore, some taxa bear the remnants of Criocardium's row of small spines connected by a striation in the rib interspaces. The Maastrichtian Perucardia has an intermediate morphology, with the anterior and posterior slopes as in the Cretaceous Criocardium while the central slope has the ribbing pattern of Cenozoic cardiids.Cladistic analysis demonstrates that Cretaceous cardiids once put into the Neogene genera Fragum and Bucardium are allied with Criocardium. Species placed in Fragum resemble that genus only in its trigonal shell shape; they share the interspace spines and several other characters witth Criocardium and belong in Profragum Badve 1977. Species placed in Bucardium on the basis of round shell shape and reduction in rib number are properly placed in Austrocardium Freneix and Grant-Mackie 1978, and share the interspace striation and other characters with Criocardium. Austrocardium is another example of rib fusion: a groove, homologous to a rib interspace, runs down the top of each rib; this accounts for the reduction in rib number.A third example of rib fusion occurs in some species of the Cenozoic genus Hedecardium. Two ribs (each one homologous to a pair of ribs in Granocardium) undergo an additional episode of fusion, forming a single rib with two parallel rows of spines and striations on top of the rib; a single one of these ribs would therefore be homologous to four ribs on Granocardium.Fusion of iterative homologues has been discerned in many arthropods. Pairs of metameric segments have fused, leaving individual segments with twice the number of anatomical structures usually associated with a single segment. Radial ribs are not metameric (but are iterative) since they radiate from a single point as opposed to being repeated in a linear sequence. Rib fusion operating alone would imply a fifty per cent reduction in rib number, and in Austrocardium the rib number is halved. Cenozoic cardiids have fewer ribs than their Cretaceous ancestors, but only by about twenty per cent. Fusion is only one of several processes that regulate rib number on cardiids.

Parasternal sonography of the internal mammary vessels: technique, normal anatomy, and lymphadenopathy.

Metastasis to the internal mammary lymph nodes adversely affects the disease-free interval and long-term survival in women with breast carcinoma. Since staging of disease in this lymphatic chain is rarely performed at the time of definitive surgical treatment, noninvasive methods have been advocated. The authors present their preliminary experience with a sonographic technique for evaluating the internal mammary lymph nodes, artery, and vein. Longitudinal and transverse images of the first through fourth parasternal rib interspaces were acquired with a 5.0- or 7.5-MHz linear-array real-time system. The method was evaluated prospectively in 36 control subjects and in seven patients (six with metastatic breast cancer and one with lymphocytic lymphoma) who had enlarged internal mammary lymph nodes at thoracic computed tomography (CT). The longitudinal scans routinely demonstrated the internal mammary vessels in the upper interspaces. Lymphatic structures were not identified in the control group. In contrast, sonographic findings corresponding to the CT findings of lymphadenopathy were present in all seven patients. The authors believe that parasternal sonography is a promising technique that merits further study.

Subpleural lipoma.

Lipomas, which are relatively common in the subcutaneous tissues, occur only rarely in the thoracic cavity. In this position, they are usually related to the mediastinum (6, 7, 8, 12). Even rarer is the occurrence of subpleural or parietal tumors unconnected with the mediastinum. Three such cases were treated in The New York Hospital during the past five years. Case Reports Case I (Fig. 1): A 14-year-old white boy was admitted to the hospital because of an abnormal routine chest film, which had been taken two weeks previously. It demonstrated a 4 × 7 × 8-cm. density in the right posterior chest wall, opposite the sixth rib interspace. There was localized widening of the rib interspace with attenuation of the adjacent sixth and seventh ribs. On physical examination, a firm, nontender, 4 × 4-cm. mass was found to the right of the spine at the midscapular level, corresponding in position to the density on the chest film. At operation a large, yellow, fatty, dumbbell-shaped mass was found, extending from outside the chest wall through the sixth interspace into the posterior thoracic cavity. The entire mass was excised, and the pathological report was lipoma. Case II (Fig. 2): A 72-year-old white woman was admitted to the hospital without complaints. Two weeks prior to admission she fell, and roentgenograms were taken of the right shoulder for possible fracture. There was no evidence of bone injury, but a density was fortuitously discovered in the right chest. It measured 2 × 3.5 cm. and was adjacent to the lateral chest wall. Exploratory thoracotomy was undertaken and revealed a yellow, encapsulated, subpleural mass. Its base was in the intercostal space but did not penetrate it. The mass was resected and the pathological report was lipoma. Case III (Fig. 3): A 69-year-old white woman was admitted to the hospital for a retinal detachment. A routine chest film revealed a 3.5 × 4-cm., sharply circumscribed density in the left upper lung field adjacent to the lateral chest wall. A left thoracotomy was performed and a soft subpleural mass was found bulging into the pleural cavity. The mass, which did not penetrate the rib interspace, was completely removed. The pathological report was lipoma. Discussion Heuer (6, 7) divided intrathoracic lipomas into three groups: (a) hourglass tumors consisting of an intrathoracic and extrathoracic mass connected by a thin isthmus perforating the thoracic wall between the ribs; (b) anterior superior mediastinal masses which extend up into the root of the neck, presenting as visible and palpable tumors; (c) wholly intrathoracic masses, which are most commonly related to the mediastinum. Those masses separated from the mediastinum have been designated as subpleural lipomas and may be located beneath the costal or diaphragmatic pleura (2, 13). They are rare in the latter location.