Cortical desmoid and the four clinical scenarios

Pseudolesions involving bone and soft tissue regarding orthopedic oncology

Pseudolesions in bone and muscle are encountered mostly incidentally in routine imaging studies, especially due to the recent advancements on many different imaging modalities. These lesions can be categorized into the following categories: normal variants; congenital; iatrogenic; degenerative; and postoperative. In this review, we discuss the many different radiological characteristics of musculoskeletal pseudolesions that appear on imaging, which can prevent non-essential additional studies.

Tumor-Like Distal Femoral Cortical Irregularities of the Knee in Adolescent Competitive Alpine Skiers: Longitudinal Assessment Over 48 Months

BACKGROUND

Tumor-like distal femoral cortical irregularities (DFCIs) are a frequent incidental finding on knee magnetic resonance imaging (MRI) and are common in young competitive athletes.

PURPOSE

To assess and compare the morphology and prevalence of DFCIs in competitive alpine skiers over 48 months during adolescence.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Adolescent competitive alpine skiers were prospectively recruited in 2018 and received bilateral 3-T MRI of the knee at baseline and after 48 months. All MRIs were evaluated for the presence and location of DFCIs, which were marked at 1 of 3 anatomic positions: (1) the femoral attachment of the medial head of the gastrocnemius muscle, (2) the lateral head of the gastrocnemius muscle, or (3) the attachment of the adductor magnus aponeurosis. The size of the DFCI was measured by 2 radiologists independently. The measurements were compared using the Wilcoxon signed-rank test, the interclass correlation coefficient (ICC), and Cohen Kappa.

RESULTS

A total of 63 athletes (mean age at follow-up, 19.6 ± 1.2 years; n = 25 female) were included in the study. At baseline, DFCIs were detected in 84 out of 126 knees (67%). At the 48-month follow-up, DFCIs were found in 88 out of 126 knees (70%), with multiple DFCIs in 3 knees and no significant difference between male and female patients (n = 24 male, n = 19 female; P = .71). No significant increase was detected for the number (P = .21) and size of the DFCIs between the baseline and the 48-month follow-up (mean size: baseline, 3.7 ± 0.8 mm; 48-month follow-up: 3.6 ± 0.9 mm; P = .66). The interrater agreement for the mean size measurements of DFCIs was good to excellent (ICC 0.88).

CONCLUSION

DFCIs remain a frequent finding on knee MRI in competitive alpine skiers after skeletal maturation and do not disappear during adolescence. The DFCI size was constant in athletes aged between 15 and 19 years. Moreover, DFCIs should not be mistaken for a pathologic finding.

Metaphyseal and Diaphyseal Contours: Variants and Pitfalls

We discuss several variants of the metaphyseal and diaphyseal bone surfaces that may be misleading in clinical practice. They include metaphyseal stripes, spiculated metaphyseal cortex, cortical desmoid, laminated lateral supracondylar ridge, cortical vascular canals, variations in shape or lucency of normal tuberosities, cortical thickening of normal ridges, and well-organized undulated hyperostosis at the proximal phalanges.

Cortical Desmoid of the Distal Femur-Incidentaloma or Insertional Tendinopathy?

BACKGROUND

The cortical desmoid (DFCI) of the posteromedial femoral condyle is considered an asymptomatic incidental finding in adolescents without clinical relevance. The aim of this study was to evaluate the clinical relevance of DFCI from both a tumor orthopedic and sports medicine point of view.

METHODS

n = 23 patients (13.74 ± 2.74 years; nineteen female, four male) with DFCI of the posteromedial femoral condyle were included. A localized posteromedial knee pain on exertion was differentiated from non-specific knee pain. Symptom duration, additional pathologies, number of MRIs, sports activity and training intensity, downtime, therapeutic modalities, and relief/remission of symptoms were documented. The Tegner activity scale (TAS) and Lysholm score (LS) were collected. The influence of specific posteromedial pain, MRI presence of paratendinous cysts, sports level as well as physiotherapy on downtime and LS/TAS was statistically analyzed.

RESULTS

100% reported knee symptoms at initial presentation. A localized posteromedial pain was documented in 52%. In 16/23 (70%) additional functional pathologies were diagnosed. Patients were physically highly active with high training intensities (6.52 ± 5.87 h/week) and performance level (65% competitive vs. 35% recreational). Patients underwent 1.91 ± 0.97 MRIs (max four). Symptom duration was 10.48 ± 11.02 weeks. A follow-up examination was performed after 12.62 ± 10.41 months (n = two lost to follow-up). 17/21 had physiotherapy, on average 17.06 ± 13.33 units. Overall downtime was 13.39 ± 12.50 weeks, the return-to-sports (RTS) rate 81%. 100%/38% reported a relief/remission of complaints. LS was 93.29 ± 7.95, median TAS before onset of knee complaints/at follow-up 7 (6-7)/7 (5-7). Specific posteromedial pain, presence of paratendinous cysts, sports level and physiotherapy had no significant influence on downtime and outcome parameters (n.s.).

CONCLUSIONS

DFCI as a pathognomonic finding is recurrently encountered in the MRIs of children and adolescents. This knowledge is essential to spare patients from overtreatment. Contrary to the literature, the present results implicate a clinical relevance of DFCI particularly in those who are physically highly active with localized pain on exertion. Structured physiotherapy as basic treatment is recommended.

Scaphoid Cortical Desmoid in a Snowboarder With Persistent Wrist Pain

A 28-year-old man presented to our clinic with persistent left wrist pain. Three months earlier, he had fallen on an outstretched hand while snowboarding. Initial radiographs showed no fractures or dislocations; however, magnetic resonance imaging revealed evidence of a dorsal projection from the scaphoid waist. There was no evidence of a scaphoid wrist fracture, scapholunate ligament disruption, or injury. The final diagnosis was avulsive cortical irregularity or cortical desmoid, which pertains to new bone formation at sites of muscle insertion. The literature has identified cases found in the deltoid, latissimus dorsi, adductor magnus muscles, and gastrocnemius insertion; however, it has never been reported in the scaphoid region. The proposed mechanism, in this case, is the repetitive pull on the radioscaphoid ligament. Avulsive cortical irregularities are benign conditions that mimic malignant conditions radiologically and microscopically. It is therefore important not to mistake this lesion for more worrisome lesions such as osteosarcoma or fibrosarcoma to avoid unnecessary procedures. In the incidental setting, no further imaging is necessary. If the patient presents with pain, atypical radiographical findings, or a suspicion of malignancy, a magnetic resonance image can provide valuable information and confirmation of diagnosis.

Distal Femoral Cortical Irregularity at Knee MRI: Increased Prevalence in Youth Competitive Alpine Skiers

Background Tumor-like cortical irregularities at the posterior distal femur are common incidental findings in adolescents, but the origin of these irregularities is debated. Purpose To compare the prevalence of distal femoral cortical irregularities (DFCIs) at different tendon attachment sites in youth competitive alpine skiers with that in young adults. Materials and Methods In this secondary analysis of a prospective trial, unenhanced 3-T knee MRI scans obtained in youth competitive alpine skiers were compared with images in control participants of the same age from 2014 to 2019 (Cantonal Ethics Committee Zurich registry number: KEK-ZH-2017-01395) for presence of DFCIs at the femoral attachment of the medial head of the gastrocnemius muscle (MHG) and/or lateral head of the gastrocnemius muscle (LHG) and adductor magnus tendon by two radiologists. DFCI size and tendon attachment position were measured. Tendon attachment position and associated MRI findings (meniscus, cartilage, bone marrow edema, joint effusion, ligaments, tendons) were examined for an association with DFCI. Pearson χ², Student t test, logistic regression, and κ statistics were applied. Results Unilateral knee MRI scans obtained in 105 skiers (mean age, 14.8 years ± 0.6 [standard deviation]; 66 boys) and in 105 control participants (mean age, 14.6 years ± 0.5; 59 boys) were evaluated. DFCIs were found in 61 of 105 skiers (58%; 95% confidence interval [CI]: 48.5%, 67.2%) compared with 28 of 105 control participants (27%; 95% CI: 18.9%, 35.7%) (P < .001). Two skiers had more than one DFCI. Distribution of DFCIs for skiers and control participants was 60 of 63 (95.2%) and 26 of 28 (92.8%) at the MHG, three of 63 (4.8%) and one of 28 (3.6%) at the LHG, and zero of 63 (0%) and one of 28 (3.6%) at the adductor magnus attachment site, respectively. Interreader agreement was almost perfect (κ = 0.87; 95% CI: 0.80, 0.93). The mean size of MHG-related DFCIs in skiers (3.7 mm) was not different compared to the size of those in control participants (3.4 mm) (P = .32), nor was a difference found for the MHG tendon attachment position in knees with DFCI (63.9 mm vs 63.0 mm, P = .83) or without DFCI (63.6 mm vs 62.8 mm, P = .86). Regarding associated MRI findings, increased signal intensity of the MHG tendon showed a significant association with MHG-related DFCI in both groups (P = .01 for both). Conclusion A distal femoral cortical irregularity at the attachment sites of tendons was a frequent incidental finding on knee MRI scans, with an increased prevalence in youth competitive alpine skiers. © RSNA, 2020 Online supplemental material is available for this article.

The aetiology of the non-ossifying fibroma of the distal femur and its relationship to the surrounding soft tissues

PURPOSE

We aim to retrospectively evaluate patients with non-ossifying fibroma (NOF) of the distal femur by radiographs, CT and MRI, and to provide a theory describing the reasoning for the distal femur NOF's location and aetiology.

METHODS

Charts of patients with NOFs between 2003 and 2014 were retrospectively reviewed. Inclusion criteria encompassed a diagnosis of NOF of the distal femur by imaging, and histologically, if available. Radiographs, CT and MRI were used to characterise the relationship of the NOF lesions with the surrounding soft tissues.

RESULTS

The 68 NOFs from 60 patients were included. By radiograph, 41 (60.3%) of the 68 lesions appeared at the medial and 25 (36.7%) at the lateral aspect of the distal femur. In total, 41 lesions had CT scans, showing 22 NOFs (53.7%) attached to the origin of the medial gastrocnemius, 12 (29.3%) to the origin of the lateral gastrocnemius and four (9.8%) at the attachment of the adductor magnus. Of the CT scans, 93% identified the NOF's relationship with an adjoining tendon of the distal femur. Six had MRIs, all of which showed attachment at the medial gastrocnemius.

CONCLUSION

The study reveals a relationship between tendinous structures and NOFs. NOFs of the distal femur occur most commonly at the origin of the medial and lateral gastrocnemius. They may originate from the physis/metaphysis but they do not always attach to the physis, as we observe them 'migrating' as patients grow. More research is required to understand the exact aetiology of NOFs.

Cortical desmoid of the humerus: radiographic and MRI correlation

Cortical desmoids are self-limiting fibro-osseous lesions commonly occurring at the medial supracondylar femur in active adolescents, at either the origin of the medial head of the gastrocnemius or at the insertion of the adductor magnus aponeurosis. Less commonly, in a similar demographic, cortical desmoids may occur in the proximal humerus medially at the insertion of the pectoralis major muscle or laterally at the insertion of the deltoid. The radiographic appearance of the proximal humerus cortical desmoid has been described previously, but not the MRI appearance. We present the radiographic and MRI appearances of a proximal humerus cortical desmoid in a young adolescent who presented for investigation of right shoulder pain.

Periosteal desmoplastic fibroma of the tibia in a 3-year-old child

Desmoplastic fibroma is a rare benign fibrogenic, locally aggressive, primary bone tumor. It is the intraosseous counterpart of soft tissue aggressive fibromatosis. The lesion may very rarely appear as a superficial bone lesion arising from the periosteum; in such cases, a soft tissue mass with changes in the adjacent bone is evident. Periosteal lesions are very rare in the literature; diagnosis is usually based on the radiographic findings, and histological proof of the tumor origin is missing. A periosteal desmoplastic fibroma of the distal tibial metaphysis in a 3-year-old boy is presented. Radiographic investigation included plain radiographs and computed tomography imaging. Both demonstrated a soft tissue lesion involving the superficial bone tissues with non-aggressive looking borders and a pressure effect with a sclerotic rim in the bone. The lesion was excised, and the surgical as well as the histological findings indicated the diagnosis of a desmoplastic fibroma of bone arising from the periosteum. No recurrence was detected 5 years after surgery.

Cortical desmoids in adolescent top-level athletes

Two adolescent, highly active athletes are presented with unspecific symptoms of anterior knee pain. Conventional radiographs and magnetic resonance imaging (MRI) showed a suspicious but pathognomonic cortical irregularity of the dorsal, medial femoral condyle. Cortical desmoid is one of the most common incidental osseous findings on conventional radiographs and MRI of the knee. It often needs no follow-up examination in asymptomatic patients. Malignancy needs however to be ruled out.

The pediatric knee

Knee pain is a common problem in children and adolescents, and MRI of the knee is the most commonly performed pediatric cross-sectional musculoskeletal imaging exam. The purpose of this pictorial review is to highlight differences between adult and pediatric knee imaging with an emphasis on normal developmental variants, injury and disease patterns unique to children and adolescents, and differences in response and presentation to conditions affecting both adults and children.

Magnetic resonance imaging of anatomical variations in the knee. Part 2: miscellaneous

Magnetic resonance imaging is the modality of choice for investigation of internal derangement of the knee. The reporting radiologist must be familiar with both normal anatomy and anatomical variants within the knee, in order to avoid mis-diagnosis, over-investigation and unnecessary intervention. This article reviews the recognised anatomical variants of the non-ligamentous/musculotendinous structures of the knee, their anatomy, incidence and typical appearances on MRI.

The incidental skeletal lesion: ignore or explore?

The ‘leave me alone’ bone lesions are very classical, and, as indicated by their name, do not require any further investigation. There are very typical cases, and there are also more difficult ones, and they can be especially difficult to manage if the patient has a known cancer.