Roopa Ram

Diabetic Myonecrosis: Likely an Underrecognized Entity

Diabetic myonecrosis is a rare complication of long-standing diabetes mellitus that presents as acute onset of swelling and pain of the affected muscles. The differential diagnosis includes cellulitis/pyomyositis, necrotizing fasciitis, neoplasm, and deep venous thrombosis (DVT). Missed diagnoses can lead to unnecessary invasive diagnostic procedures and inappropriate treatment. The diagnosis is established by the clinical presentation and findings on magnetic resonance imaging (MRI) scan. A 30-year-old African-American man presented with a painful mass affecting the medial aspect of the right thigh for several months. Initial laboratory studies showed white blood cell count of 8800 cells/mm(3), D-dimer value of 0.55 µg/mL, HgBA1c level of 15.1%, glucose level of 352 mg/dL, erythrocyte sedimentation rate of 22 mm/h, and C-reactive protein level of 222 mg/L. An MRI scan was obtained, and diabetic myonecrosis was diagnosed and treated. One year later, the patient had similar symptoms of pain in the contralateral thigh. Repeat workup and MRI scan were obtained. The MRI abnormalities originally seen in the right thigh 1 year earlier were present in the left thigh, with complete resolution of the abnormalities seen in the right thigh. Treatment with bed rest and analgesics resulted in symptom resolution. Patients with diabetic myonecrosis typically have no fever, normal white blood cell count, mildly increased erythrocyte sedimentation rate, and elevated C-reactive protein level in 50% of cases. They lack the radiologic signs of fascial enhancement or well-defined, rim-enhancing collections that are seen in necrotizing fasciitis and pyomyositis/abscess. The onset of severe pain and the lack of mass effect on imaging differentiate diabetic myonecrosis from tumor-like conditions such as vascular malformations or soft tissue tumors. Normal D-dimer levels and ultrasound Doppler examination of the extremity help to rule out DVT. The typical MRI scan findings and clinical presentation can lead to the diagnosis of diabetic myonecrosis, allowing the physician to avoid invasive tests, such as muscle biopsy, and to reassure patients that this condition is self-limiting with appropriate treatment.

Imaging of Sarcoidosis : A Contemporary Review

Sarcoidosis is a systemic granulomatous disorder with a variety of clinical presentations and radiological appearances. Although it primarily affects the lungs and lymphatics, sarcoidosis potentially involves essentially every organ system. On imaging, sarcoidosis can mimic different disease entities, including primary and metastatic neoplasms, vasculitis, and other granulomatous infections. Definitive diagnosis often requires a combination of clinical, radiological, and histologic information. Imaging plays a crucial role in diagnosis and evaluating response to therapy. This review covers imaging findings in sarcoidosis within each organ system, with an emphasis on the use of imaging in the diagnosis and management of this condition.

High Relative Expression of Pannexin 3 (PANX3) in an Axillary Sweat Gland Carcinoma With Osteosarcomatous Transformation.

Primary cutaneous sweat gland carcinomas (SGCs) are rare tumors that commonly involve axillae, have a high local recurrence rate, and rarely show sarcomatoid transformation. A 68-year-old man presented with rapid enlargement of a previously stable, asymptomatic pea-sized nodule in the left axilla. Initial excision (with positive surgical margins) at another institution showed characteristic histologic features of a high-grade osteosarcoma and molecular analysis using a 92-gene real-time quantitative reverse transcription-polymerase chain reaction assay confirmed a diagnosis of osteosarcoma with 96% certainty. Notably, the molecular assay demonstrated consistently high relative expression of pannexin 3 (PANX3), a gene involved in normal osteoblast differentiation which, when highly expressed, strongly predicts osteosarcoma per the assays algorithm. However, on further histologic review, the tumor also contained focal cystic areas, nests, and ducts composed of malignant epithelial cells reminiscent of SGC; these areas directly transitioned into the osteosarcomatous component and were strongly positive for pancytokeratin, CK7, and p63. Within 2 weeks, the lesion recurred and grew rapidly, prompting complete resection, histologic sections of which showed high-grade osteosarcoma without residual epithelial elements. This is the fifth report, to our knowledge, of osteosarcomatous transformation in a SGC, and the only report to date including molecular data. This case demonstrates that osteosarcoma arising from a SGC has a similar molecular profile to de novo primary osteosarcoma of bone. It also emphasizes the importance of histopathologic findings as the established diagnostic gold standard and the need to interpret molecular results within the clinical context.

A rare case of extra nodal Rosai-Dorfman disease with isolated multifocal osseous manifestation.

Sinus histiocytosis with massive lymphadenopathy (SHML) or Rosai–Dorfman disease is a non-neoplastic condition which typically presents as massive, bilateral cervical lymphadenopathy and can involve multiple extranodal organ systems such as skin, eyes, and upper respiratory tract in about 28% cases. Bone lesions in association with nodal disease are seen in less than 10% cases. Isolated bone involvement as the only manifestation of SHML is extremely rare, with less than 50 cases reported in the literature. We report a very uncommon case of Rosai–Dorfman disease with isolated multifocal osseous involvement as the only presenting feature, involving about 10 different sites with no lymphadenopathy or other organ system involvement.

Imaging of Pelvic Floor Reconstruction

Stress urinary incontinence and pelvic organ prolapse are 2 common pelvic floor disorders that are important causes of pelvic pain and disability. Mesh and sling placement are some of the surgical treatment options available for treatment of these conditions. In addition to clinical assessment, imaging plays an important role in managing postoperative patients with complications such as recurrent organ prolapse and chronic pain. Role of high-resolution pelvic magnetic resonance imaging with additional advanced imaging techniques, such as magnetic resonance neurography that are invaluable in managing such patients, are discussed in this article.

Malignant Triton Tumor (Malignant Peripheral Nerve Sheath Tumor With Rhabdomyoblastic Differentiation) Occurring in a Vascularized Free Flap Reconstruction Graft

Malignant peripheral nerve sheath tumor (MPNST) is a rare form of sarcoma arising from Schwann cells or pluripotent cells of the neural crest. Malignant triton tumor (MTT) is a subtype of MPNST with a component of malignant rhabdomyoblasts in addition to malignant Schwann cells. MPNST and MTT are both aggressive malignancies that most commonly arise from large deep neurofibromas in patients with neurofibromatosis type 1 (NF-1). However, sporadic non-NF-1 cases of MTT have also been reported in the literature. We present a case of a 50-year-old African American male with no stigmata of NF-1 who developed a large mass in a free flap on the right calf. The free flap had been placed by plastic surgery 15 years previously following open right tibial and fibular fractures associated with a large soft tissue defect. Biopsy of the enlarging mass, followed by wide surgical excision, confirmed the pathology to be MTT. Although the development of a high-grade soft tissue sarcoma has been previously reported as a late complication of radiation therapy following free flap reconstructions, we believe this is the first reported case of sarcomatous transformation arising in a vascularized, free muscle transfer.

Magnetic resonance enterography: A stepwise interpretation approach and role of imaging in management of adult Crohn's disease.

Crohns disease (CD) is a chronic inflammatory bowel disease that often requires frequent imaging of patients in order to detect active disease and other complications related to disease activity. While endoscopy is the gold standard for diagnosis, it may be contraindicated in some patients and has a limited role in detecting deep submucosal/mesenteric diseases and intra abdominal complications. In recent years, magnetic resonance enterography (MRE) has evolved as a noninvasive, radiation free imaging modality in the evaluation of patients with CD. This review article will focus on role of MRE in imaging patients with CD with emphasis on technical considerations, systematic image interpretation, differential diagnoses, and the role of imaging in deciding treatment options for patients.

Diffuse infiltrative neurofibroma: a clinical, radiological, and histological conundrum

Diffuse infiltrative neurofibroma is a rare clinical entity that can pose a diagnostic challenge not only due to its rarity but also due to its varied clinical, radiological, and histological features. Our case illustrates how this entity may be misdiagnosed on clinical and pathological examination. Radiological imaging plays a critical and collaborative role in guiding clinicians and pathologists when faced with this challenging diagnosis.

Dedifferentiated Liposarcoma Mimicking a Primary Colon Mass

Dedifferentiated liposarcoma is typically a nonlipogenic high-grade sarcoma that arises from well-differentiated liposarcoma. It most commonly presents as a large mass in the retroperitoneum. Significant involvement of the gastrointestinal tract by dedifferentiated liposarcoma is uncommon. We present a unique case of dedifferentiated liposarcoma radiographically mimicking a primary colon mass with resulting intussusception; stranding of the adjacent adipose tissue was presumed to be a secondary reactive change. On histopathologic analysis of the hemicolectomy specimen, a high-grade sarcoma was seen growing through the colonic wall, and the majority of the surrounding pericolonic adipose tissue was actually composed of well-differentiated liposarcoma with characteristic fibrous bands rather than benign fat with reactive fibrosis. This case raises awareness that well-differentiated liposarcoma and dedifferentiated liposarcoma can rarely present as a primary intestinal mass mimicking colon cancer or other more common entities. When radiographic examination shows a perigastrointestinal or retroperitoneal fatty mass and/or stranding of the fat adjacent to a solid gastrointestinal mass, this unusual scenario should be considered in the radiologic differential diagnosis. Pathologists should keep dedifferentiated liposarcoma in the initial histologic differential diagnosis for any high-grade spindle cell tumor of the retroperitoneum or intra-abdominal visceral organs.

Preoperative MRA for Patient Selection in Free Fibula Flap: Is a Venous Phase Indicated?

Objectives: We present our institutional experience with dynamic time-resolved magnetic resonance angiography (DTR MRA) with delayed venous imaging for free fibula flap (FFF) patient selection. We sought to (1) determine the sensitivity of the test for vascular anomalies predisposing to limb-threatening complications and (2) assess the impact of the venous phase findings in patient selection. Methods: Retrospective review of 46 patients considered for mandibular reconstruction with FFF in an academic tertiary setting from 2009-2012. A DTR MRA was performed preoperatively in all cases. Both imaging and physical examination findings were used to determine patient eligibility for the procedure. Results: Thirteen patients (28.2%) had findings on DTR MRA excluding flap harvesting from the preferred leg, with atherosclerosis (n = 8) and anatomic variations (n = 4) being the most common findings. Eight of these patients (61.5%) underwent harvesting from the opposite leg, while 5 underwent reconstruction with a different bony flap. Only 2 of these 13 patients (15.3%) had physical examination findings excluding reconstruction with FFF. DTR MRA was significantly more likely to detect potentially limb threatening vascular anomalies than physical examination (P = .004). There was 1 patient with an anomaly on delayed venous imaging (asymptomatic deep venous thrombosis–thrombophlebitis) which excluded flap harvesting from the affected leg. Both arterial phase imaging and physical examination were normal in this patient. Conclusions: DTR MRA is significantly more sensitive than physical examination in detecting limb-threatening anatomic variations and vascular pathology prior to FFF reconstruction. The venous phase allows identification of oligosymptomatic venous anomalies that, while uncommon, may predispose to significant morbidity. These findings justify routine use of this imaging modality.