An unusual case of metastatic melanoma in subcutaneous tissue presenting as a solitary cystic mass with fluid levels

Malignant melanoma is a common and often aggressive neoplasm of the skin arising from melanocytes. Metastatic melanoma is known for its diverse clinical manifestations, and can present with atypical features prior to diagnosis of the primary lesion, which can pose a diagnostic challenge. We report a rare case of metastatic melanoma in a 67 year-old male who presented with a painless, enlarging mass in the right axilla over a 4 week period. Ultrasound and magnetic resonance imaging (MRI) scans revealed a well-defined solitary, cystic appearing lesion in the right axilla with a distinct fluid-fluid level. An ultrasound guided biopsy of the lesion diagnosed a metastatic melanoma. While haemorrhagic distant metastases are a well-recognised complication of malignant melanoma, particularly in the brain and lung, soft tissue metastases presenting with fluid-fluid levels is not well described in the literature. The case highlights the importance of considering the differential of melanoma metastasis when encountered with such a lesion and importance of ultrasound guided biopsy for histopathological confirmation, as the imaging features can mimic that of a haemorrhagic soft tissue sarcoma, the management of which differs substantially from that of melanoma.

Botryomycosis: a rare mimic of sarcoma as an initial presentation of acquired immunodeficiency syndrome

Botryomycosis is a rare granulomatous response to chronic bacterial infection most frequently associated with Staphylococcus aureus. This disease, which predominantly affects immunocompromised patients, may present with cutaneous, visceral, or soft tissue manifestations. Soft tissue involvement typically has an aggressive mass-like appearance on imaging which can be concerning for malignancy. In immunocompromised patients, botryomycosis can resemble fungal infection both clinically and histologically; therefore, definitive diagnosis requires tissue sampling along with histological and microbiological analysis. Presented here is a 25-year-old man with an enlarging intramuscular soft tissue mass of the right forearm as his first presentation of undiagnosed acquired immunodeficiency syndrome (AIDS). MR imaging showed a mildly T2 hyperintense and enhancing mass with infiltrative margins extending through tissue planes. Biopsy of the mass revealed Staphylococcus aureus-associated botryomycosis, which improved with nonsurgical treatment employing antibiotics. Unfortunately, the patient subsequently expired from other manifestations of his new AIDS diagnosis. This case describes the MR and PET-CT appearance of botryomycosis and also underscores that infection can mimic sarcoma, particularly in the setting of immunodeficiency.

Update of pediatric soft tissue tumors with review of conventional MRI appearance-part 2: vascular lesions, fibrohistiocytic tumors, muscle tumors, peripheral nerve sheath tumors, tumors of uncertain differentiation, and undifferentiated small round cell sarcomas

There are numerous soft tissue tumors and tumor-like conditions in the pediatric population. Magnetic resonance imaging is the most useful modality for imaging these lesions. Although certain soft tissue lesions exhibit magnetic resonance features characteristic of a specific diagnosis, most lesions are indeterminate, and a biopsy is necessary for diagnosis. We provide a detailed update of soft tissue tumors and tumor-like conditions that occur in the pediatric population, emphasizing each lesion's conventional magnetic resonance imaging appearance, using the recently released 5^th edition of the World Health Organization Classification of Soft Tissue and Bone Tumors as a guide. In part one of this review, pediatric tumor-like lesions, adipocytic tumors, fibroblastic and myofibroblastic tumors, and perivascular tumors are discussed. In part two, vascular lesions, fibrohistiocytic tumors, muscle tumors, peripheral nerve sheath tumors, tumors of uncertain differentiation, and undifferentiated small round cell sarcomas are reviewed. Per the convention of the WHO, these lesions involve the connective, subcutaneous, and other non-parenchymatous organ soft tissues, as well as the peripheral and autonomic nervous system.

Update of pediatric soft tissue tumors with review of conventional MRI appearance-part 1: tumor-like lesions, adipocytic tumors, fibroblastic and myofibroblastic tumors, and perivascular tumors

There are numerous soft tissue tumors and tumor-like conditions in the pediatric population. Magnetic resonance imaging is the most useful modality for imaging these lesions. Although certain soft tissue lesions exhibit magnetic resonance features characteristic of a specific diagnosis, most lesions are indeterminate, and a biopsy is necessary for diagnosis. We provide a detailed update of soft tissue tumors and tumor-like conditions that occur in the pediatric population, emphasizing each lesion's conventional magnetic resonance imaging appearance, using the recently released 5th edition of the World Health Organization Classification of Soft Tissue and Bone Tumors as a guide. In part one of this review, pediatric tumor-like lesions, adipocytic tumors, fibroblastic and myofibroblastic tumors, and perivascular tumors are discussed. In part two, vascular lesions, fibrohistiocytic tumors, muscle tumors, peripheral nerve sheath tumors, tumors of uncertain differentiation, and undifferentiated small round cell sarcomas are reviewed. Per the convention of the WHO, these lesions involve the connective, subcutaneous, and other non-parenchymatous-organ soft tissues, as well as the peripheral and autonomic nervous system.

Nodular fasciitis of the anterior chest wall mimicking myxofibrosarcoma: A case report and literature review

Nodular fasciitis is a benign tumor of soft tissues originating from the proliferation of fibroblasts and myofibroblasts, generally developing between the subcutaneous tissue and the underlying muscular layer. Nodular fasciitis predominantly localizes in the upper extremities, trunk, head and neck. Biomolecular and immunohistochemical analyses result essential to demonstrate the benign origin of the process, also confirmed by very low recurrence rate after complete excision, which represents the gold standard for treatment. We report the case of a 36 years-old man who developed a nodular protuberance clinically evident in the upper-left side of the thorax. We further, highlight the main characteristics of this rare neoplasm trough a thorough review of the literature.

The differential diagnosis of trunk and extremity dermal and sub-dermal lesions referred to a musculoskeletal oncology service

OBJECTIVES

To determine the differential diagnosis of dermal and sub-dermal soft tissue masses which do not extend to the deep fascia that are referred to a specialist musculoskeletal oncology service.

MATERIALS AND METHODS

Review of all patients referred to a specialist musculoskeletal oncology service over a 13-month period with a dermal or sub-dermal soft tissue mass which did not extend to the deep fascia based on MRI appearances. Data collected included age, gender, site and maximal lesion size, and final histological diagnosis for biopsied and/or excised lesions.

RESULTS

56 patients were included, 21 (37.5%) males and 35 (62.5%) females with mean age 49.75 years (range 5-86 years). 3 patients had 2 lesions making a total of 59 lesions, 11 (18.6%) dermal and 48 (81.4%) sub-dermal. Histological diagnosis was available in 44 (74.6%) cases, of which 11 (25%) were non-neoplastic, 23 (52.3%) were benign neoplasms, and 10 (22.7%) were malignant neoplasms. Although older age at presentation and greater mean maximal tumour dimension were seen with malignant lesions, these did not reach statistical significance (p = 0.154 and 0.102 respectively). There was also no relationship between skin involvement from sub-dermal lesions and malignancy, but 5 of 6 dermal lesions which showed an exophytic growth pattern were malignant.

CONCLUSIONS

The differential diagnosis of dermal and sub-dermal lesions which do not reach the deep fascia is wide with a malignant lesion being the cause in almost one-quarter of cases.

MRI evaluation of solid soft tissue masses of the fingers with pathology correlation

OBJECTIVE

Space occupying lesions of the fingers are commonly encountered in clinical and radiology practice. The objective of this study was to determine the characteristics of these lesions on MRI and to correlate with surgical pathology results.

MATERIAL AND METHODS

This IRB-approved HIPAA-compliant study retrospectively evaluated the clinical, imaging and pathology findings of 100 consecutive patients referred for evaluation of solid soft tissue masses of the fingers. Only solid lesions with MR imaging prior to surgery were included in this study. MR images and when available corresponding radiographs were evaluated by two radiologist in regard to signal characteristics, relation to surrounding structures and enhancement. All masses were classified into different groups based on pathology results.

RESULTS

Tenosynovial giant cell tumor (TSGCT) and fibroma of the tendon sheath were the most common solid tumors (36 %) and malignant tumors represent only 5% of the cohort. 70 % of masses with low T2 signal were TSGCT and fibroma of tendon sheath; 100 % of masses with peripheral high T2 signal and central low T2 signal/thrombus were vascular lesions, representing 41 % of the total vascular lesions in the cohort. Additionally, 100 % of serpiginous/tubular shaped masses were vascular lesions and 67 % of masses with infiltrative borders were malignant masses. Enhancement was important in identifying solid lesions but there was no statistical difference between groups related to enhancement pattern. There was a good agreement for all analyses between both readers.

CONCLUSION

Typical MR findings can help to narrow the differential diagnosis in the evaluation of finger masses and provide crucial information to guide further management.

Diffuse skeletal muscle extramedullary plasmacytomas: a rare case and review of the literature

Extramedullary plasmacytomas are rare neoplasms arising from proliferations of monoclonal plasma cells. In primary form, these malignancies occur without other sites of plasma cell disease. Secondary extramedullary plasmacytomas occur in association with multiple myeloma and may be discovered during initial intramedullary disease or may occur during multiple myeloma relapse. In very rare instances, secondary extramedullary plasmacytomas have multifocal skeletal muscle involvement. We present a case of multifocal skeletal muscle plasmacytomas in a 58-year-old man with shoulder-reduced range of motion, pain, and a history of previously treated multiple myeloma. To our knowledge, the patient's unique relapse presentation of torso and shoulder soft tissue masses and the vast extent of skeletal muscle involvement are unique to cases in the current literature. This case also has MRI findings of a muscular plasmacytoma with internal hemorrhage which has not been previously reported. This case report will review imaging features and clinical presentations of intramuscular extramedullary plasmacytomas. Since imaging surveillance for multiple myeloma relapse is commonly performed, radiologists should be aware of these uncommon relapsing features including multifocal intramuscular masses which may contain internal hemorrhage.

Case report: Back pseudocyst of unknown origin

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Pseudocysts are defined as encapsulated fluid collections not lined by epithelium.

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The etiology of pseudocysts is highly variable and can be related to trauma, inflammation, or surgery.

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Morel-Lavallee lesion also known as closed degloving injury or post traumatic pseudocyst usually arises secondary to trauma or shearing force.

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Soft tissue masses are frequently reported complaints while nonpancreatic pseudocysts remain rare entities.

Introduction

Soft tissue masses are fairly encountered clinical entities. Among the rare forms of soft tissues masses are non-pancreatic pseudocysts which are defined as encapsulated fluid collections not lined by epithelium. We are presenting a rare case of a pseudocyst of the back located within the paravertebral muscles at a tertiary care center.

Case description

Patient presented with a progressively enlarging painless back mass. CT scan was done which showed a 10 × 10 cm cystic lesion along the paravertebral muscles of the back. Surgical excision of the mass was performed revealing an irregularly shaped multilocular cyst. Final pathology showed the lesion to be a pseudocyst.

Discussion

Pseudocysts can arise in a variety of locations such as omentum, adrenal glands, spleen or lungs. The etiology of these pseudocysts is highly variable and can be related to trauma, inflammation, or surgery. The diagnosis of these entities requires proper imaging and histopathologic examination.

Conclusion

Pseudocysts arise due to a myriad of conditions and their diagnosis remains a challenge. Our case comprises the first reported case of idiopathic pseudocyst of the back. Although rare, pseudocysts should be considered in the differential of unexplained masses.

Ectopic breast tissue presenting as an enlarging abdominal mass

Ectopic breast tissue (EBT) is an uncommon entity that occurs in about 6% of the population, more frequently in Asian people. It manifests as a nonspecific soft tissue mass that can develop in any location along the "milk-line," with the axilla being the most frequently reported location. As with normal breast tissue, both benign and malignant processes can arise from EBT. Therefore, imaging plays an important role in the adequate assessment of these soft tissue lesions, characterizing its shape, borders, internal components, and vascularity, as well as its relationship with the deep fascia and adjacent structures. Here we present a case of a 33-year-old female Indian patient with an 8 cm soft tissue mass in the upper left abdominal quadrant with a recent increase in size. Clinical and imagiological evaluation were nonspecific but established the nonaggressive behavior of the lesion. To ultimately exclude malignancy, an ultrasound-guided biopsy was performed providing the histological diagnosis of EBT. This case report illustrates the value of clinical, radiological, and histological correlation in the approach of indeterminate soft-tissue tumors, with special focus on lesions in close proximity to the native breasts, where EBT should not be forgotten amongst differentials.

Soft Tissue Tumors of the Extremity

Although the vast majority of soft tissue extremity masses are benign, approximately 13,000 people in the United States were diagnosed with soft tissue sarcoma in 2019. This article focuses on the optimal workup of soft tissue masses including the indications for ultrasound and MRI, as well as use of preoperative core needle biopsy. Current AJCC staging, surgical principles of soft tissue sarcoma management, and data regarding indications for radiation therapy and chemotherapy are reviewed. As up to 50% of patients with soft tissue sarcoma will develop recurrent disease, surgical management of locally recurrent and distant metastatic disease is discussed.

Chondroid lipoma: multimodality imaging in a 9-year-old female

Chondroid lipomas are rare, benign lipomatous tumors that occur most frequently in adults during the fourth decade of life. While a female predominance was observed in the initial series of 20 cases described in 1993, the subsequent 49 reported cases do not support a strong gender predilection. We report a case of a chondroid lipoma presenting in a 9-year-old female as a painless, enlarging, left gluteal mass. This is the second case to be reported in the first decade of life and the fourth pediatric case reported in the literature (age < 21). We review the imaging and pathology findings as well as present a comprehensive review of the current literature.

Recurrent myxoid liposarcoma of the hand

Malignant hand tumors are rarely observed in clinical practice which makes distinguishing them from benign soft tissue masses particularly challenging. A 41-year-old male presented with joint pain and swelling of his left index metacarpophalangeal joint. Radiological studies showed pronounced swelling around the affected joint with no bony abnormality, but incision and drainage of the site yielded negative cultures. Subsequent gross total resection confirmed the diagnosis of myxoid liposarcomas after cytogenetic pathology examination. Recurrence occurred after 1 year, followed by second resection and adjuvant radiotherapy. At 2 years follow-up, the patient was recurrence free. In conclusion, myxoid liposarcoma should be in the differential diagnosis of an older patient with erythema and swelling surrounding a subfascial mass of the hand.

Small soft tissue masses indeterminate at imaging: histological diagnoses at a tertiary orthopedic oncology clinic

OBJECTIVE

To review histologic diagnoses of soft-tissue masses (STMs) ≤ 2 cm with indeterminate imaging features encountered in musculoskeletal oncology clinic at a tertiary referral center.

MATERIALS AND METHODS

This was an IRB-approved retrospective review of patients with STMs ≤ 2 cm, referred to our tertiary care orthopedic oncology clinic over 4.75 consecutive years. Maximum diameter was based on imaging measurement by a fellowship-trained musculoskeletal radiologist. Simple lipomas, synovial cysts, metastases, and cases without histologic confirmation were excluded. Patient demographics, tumor imaging features (location, depth, size, and tumor:muscle enhancement and T2 signal ratios), and histology were recorded and compared.

RESULTS

Mean maximum diameter for 42 trunk/extremity STMs was 1.5 cm (range, 0.7 to 2 cm). Mean age was 48 years (range, 18-83 years). Nine (21%) of the masses were malignant, while 33 (79%) were non-malignant. Thirty-nine (93%) of masses were superficial; 7/39 (18%) of these superficial tumors were malignant. Malignancy was not associated with underlying vessels, tendon, or fascia (p = 0.19). The non-malignant vs. malignant tumor:muscle enhancement ratio was 2.15 vs. 2.32 (p = 0.58) and enhancement coefficient of variation was 0.14 vs. 0.10 (p = 0.29). Most common malignant histologic subtypes were synovial sarcoma (n = 3), fibroblastic/myofibroblastic sarcoma (n = 2), leiomyosarcoma (n = 2), myxofibrosarcoma (n = 1), and angiomatoid fibrous histiocytoma (n = 1). The majority (67%) of non-malignant lesions were: leiomyoma (n = 6), angiomyoma (n = 5), schwannoma (n = 4), benign fibrous histiocytoma (n = 4), and hemangioma (n = 3).

CONCLUSIONS

At a tertiary musculoskeletal oncology referral clinic, primary STMs ≤ 2 cm with indeterminate imaging features should be managed cautiously despite their small size and/or superficial location.

Intraluminal capillary hemangioma of the foot presenting clinically as a neuroma: A case report

Capillary hemangiomas are rarely seen in the foot, especially in the deeper soft tissue compartment. If left untreated, they can give rise to benign soft-tissue tumors. A rare case of a capillary hemangioma on the right dorsal medial midfoot that, because of its location adjacent to the saphenous nerve, mimicked the signs and symptoms of a neuroma. In addition, the patient had a history of previous surgery for neuroma excision at the same location. Despite the strong suggestion of another recurrence of a neuroma, a careful workup, including the use of MRI and multidisciplinary consultation was implemented to rule out a possible malignancy. Its nature was confirmed by careful biopsy and histopathological findings prior to surgical resection. This case illustrates how a benign vascular lesion could elicit nerve-related pain in the foot and should be distinguished from malignant tumors, such as soft tissue sarcoma, prior to surgical planning.

Extremity gossypiboma mimicking sarcoma: case report and review

A 70-year-old man with a history of bladder and colon cancer presented with an enlarging mass in his right lower extremity. Forty years before presentation, he had injured his right lower extremity in a motor vehicle accident. Imaging findings indicated suspected sarcoma, which led to biopsy. Biopsy and further surgical exploration revealed the presence of a surgical sponge and surrounding local inflammatory reaction. No neoplasm was found, and the sponge and involved tissues were removed. Gossypiboma is exceedingly rare in the extremities. Imaging of retained foreign material can appear suggestive of sarcoma because of strong inflammatory responses and local tissue mass-like derangement resulting in heterogeneous signal changes. Ultimately, biopsy must be performed to ensure that no oncological pathological condition is present.

Ultrasound of Soft Tissue Masses and Fluid Collections

Soft tissue masses and fluid collections are frequently encountered in sonographic practice, either as principal indication for diagnostic examination or as an incidental finding during an examination performed for other indications. Sonography is a good first-line imaging modality for evaluation of superficial masses and fluid collections, but requires meticulous attention to technique to avoid diagnostic pitfalls. Although many superficial masses are diagnosed with ultrasound, there are several potential diagnostic challenges, including differentiating hematomas from sarcomas. This article provides an image-rich review of the sonographic features of common soft tissue masses, with emphasis on practical tips to accurately recognize important pathology.

Diffusion weighted imaging demystified: the technique and potential clinical applications for soft tissue imaging

Diffusion-weighted imaging (DWI) is a fast, non-contrast technique that is readily available and easy to integrate into an existing imaging protocol. DWI with apparent diffusion coefficient (ADC) mapping offers a quantitative metric for soft tissue evaluation and provides information regarding the cellularity of a region of interest. There are several available methods of performing DWI, and artifacts and pitfalls must be considered when interpreting DWI studies. This review article will review the various techniques of DWI acquisition and utility of qualitative as well as quantitative methods of image interpretation, with emphasis on optimal methods for ADC measurement. The current clinical applications for DWI are primarily related to oncologic evaluation: For the assessment of de novo soft tissue masses, ADC mapping can serve as a useful adjunct technique to routine anatomic sequences for lesion characterization as cyst or solid and, if solid, benign or malignant. For treated soft tissue masses, the role of DWI/ADC mapping in the assessment of treatment response as well as recurrent or residual neoplasm in the setting of operative management is discussed, especially when intravenous contrast medium cannot be given. Emerging DWI applications for non-neoplastic clinical indications are also reviewed.

Myopericytoma/myopericytomatosis of the lower extremity in two young patients: a recently designated rare soft tissue neoplasm

Myopericytomas are rare, slow-growing benign perivascular tumors most commonly arising within the superficial subcutaneous soft tissues of the lower extremity. They represent one of several related perivascular tumors of myoid lineage with similar morphology and shared immunohistochemical profile including positive staining for smooth muscle actin. Histologically, myopericytoma exhibit concentric, perivascular proliferation of spindled myoid cells with bland elongated nuclei and associated blood vessels. A solitary well-demarcated nodule or mass is typically referred to as myopericytoma, whereas an infiltrative multinodular lesion has more recently been termed myopericytomatosis. At magnetic resonance imaging, tumors are most commonly superficial, may be well-defined (myopericytoma) or ill-defined (myopericytomatosis), and demonstrate highly vascularized, avidly enhancing soft tissue often with areas of internal hemorrhage. We report 2 cases involving the lower extremity (1 myopericytoma and 1 myopericytomatosis) occurring in young patients, focusing on the clinical, histopathologic, and radiologic characteristics of this relatively new distinct entity.

Soft tissue masses for the general orthopedic surgeon

Soft tissue sarcomas are a rare, heterogeneous group of malignancies that should be included in the differential diagnosis for any patient presenting with a soft tissue mass. This article reviews strategies for differentiating between benign and malignant soft tissue masses. Epidemiology, appropriate workup, and treatment of soft tissue sarcomas are reviewed.

A complex fistula-in-ano presenting as a soft tissue tumor

INTRODUCTION

Anorectal abscess and fistula are quite commonly encountered diseases. Both of these are the acute and chronic manifestations of the same entity. While abscess are thought to begin as an infection in the anal glands, their spreading into adjacent spaces results in a fistula formation. At many times this spread occurs in a complex pattern which is difficult to map and treat.

PRESENTATION OF CASE

This paper describes a complex perianal fistula that presented as a painless benign lump in the upper outer quadrant of the right buttock. The lump initially thought to be a soft tissue swelling was later diagnosed to be a chronic abscess cavity extending medially toward the anal canal in the form of a complex fistulous tract.

DISCUSSION

Complex perianal fistulas are difficult to treat and are prone to recurrences. Correct diagnosis and characterization of the fistula is essential to optimize the treatment. Clinical examination alone may not give a correct picture of the actual disease, thereby requiring radiological investigations like MRI.

CONCLUSION

Although rare, sometimes common clinical conditions like fistula-in-ano may also present in complex manner. It is important to establish the diagnosis firmly and map the fistula properly before going in for surgery. Complexity of fistulas and improper mapping often leads to recurrences and other complications like incontinence.

Malignant soft tissue tumors in children

Soft tissue masses are frequently seen in children. Although most are benign or reactive, soft tissue sarcomas (STS)-both rhabdomyosarcoma (most common) and non-rhabdo STS, do occur in the extremities. Appropriate evaluation of extremity soft tissue tumors often includes a biopsy as the clinical and imaging features may not be enough to establish a definitive diagnosis. Much needs to be done for improving the treatment of these rare but often devastating sarcomas. Given the small numbers of these cases seen at various centers, collaborative efforts should be made to further our understanding and improve the management of these challenging cases.

Benign soft tissue tumors in children

Soft tissue masses in children are common, yet can pose a diagnostic dilemma for the orthopedic surgeon who is asked to evaluate them. Although most lesions are dysplastic or benign, some soft tissue sarcomas are seen in the pediatric population. An understanding of the clinical presentation and imaging findings can guide the surgeon decide on the need for a biopsy and formulate an appropriate treatment plan.

Calcific myonecrosis of the antetibial area

Calcific myonecrosis is a rare late post-traumatic condition, in which a single muscle is replaced by a fusiform mass with central liquefaction and peripheral calcification. Compartment syndrome is suggested to be the underlying cause. The resulting mass may expand with time due to recurrent intralesional hemorrhage into the chronic calcified mass. A diagnosis may be difficult due to the long time between the original trauma and the symptoms of calcific myonecrosis. We encountered a 53-year-old male patient diagnosed with calcific myonecrosis in the lower leg. We report the case with a review of the relevant literature.