Pseudo-malignant osseous tumour of soft tissue

Fibro-Osseus Pseudotumor of the Digit: A Case Report and Review of Literature

Introduction

Bony subungual growths arising on the digital tip are uncommon. Among these, subungual exostosis is a common cause.

Case Presentation

We describe a 35-year-old-male patient with a rare occurrence of a fibro-osseus pseudotumor of the digit. It presents with reactive intramembranous ossification, with no continuity with the distal phalanx, helping differentiate it from a subungual exostosis. The patient presented with an asymptomatic subungual growth, lifting up the nail plate distally causing onycholysis. The characteristic clinical, radiological, and histopathological features of the case are described, which helped confirm the diagnosis.

Conclusion

Cases with fibro-osseus pseudotumor of the digit reported in literature are reviewed comprehensively. The factors helping differentiate this from the other bony tumors affecting the distal phalanx, including subungual exostosis, myositis ossificans, and osteosarcoma are also highlighted.

Non‐traumatic myositis ossificans circumscripta in the anterior abdominal wall of a seven‐year‐old Ugandan child: A case report

Myositis ossificans circumscripta (MOC) is a benign and self‐limiting heterotopic ossification in the subcutaneous fat, tendons, muscles, and nerves. It is commonly due to trauma and is frequently encountered in the arm, shoulder, thigh, and hand which are prone to trauma. Non‐traumatic MOC arising from the abdominal muscles is extremely rare. We report a case of 7‐year‐old male child with a three‐year history of progressive painless abdominal swelling in the left hypochondria region with no history of associated trauma. CT scan of the abdomen showed a well‐defined hyperdense mass in the left external oblique muscle. Histological diagnosis confirmed myositis ossificans of the external oblique muscle. The mass was removed surgically with no immediate or late complications.

Non‐traumatic MOC of the abdominal muscles is very rare. Radiological investigations are crucial in the diagnosis and for differentiating a MO lesion from other malignant soft‐tissue tumors as we demonstrated in this case report.

Benign growing mass of the digit presenting as an ulcerated mass - case report and review of the literature

A 68 year-old female presents with an ulcerated mass of the 5th digit, with rapid growth during the previous month to surgery. The mass was excised and covered with a 4th dorsal metacarpal artery perforator flap. The histologic analysis was compatible with the diagnosis of fibro-osseous pseudotumor of the digit.

Fibro-Osseous Pseudotumour of the Digit: An Illustrative Case and Review of the Literature

Fibro-osseous pseudotumour is a rare, benign ossifying tumour of soft tissue that should be considered in the differential diagnosis of any tumour affecting the digits. Clinical diagnosis is difficult and fibro-osseous pseudotumour is often mistaken for malignancy, leading to inappropriate treatment. Knowledge of its clinical and histopathological features thus allows for appropriate primary treatment, sparing the patient from unnecessary radical surgery associated with presumed malignancy. We present the case of a 48-year-old male with fibro-osseous pseudotumour affecting the right ring finger, successfully treated with local excision. This is the second reported Australian case of fibro-osseous pseudotumour, and we present an extensive review of the literature relating to the diagnosis and management of this rare tumour.

Myositis ossificans of the hand in a child: case report

Myositis ossificans of the hand is very rare. We report a case of an obviously post-traumatic case and discuss the value of trauma in the etiology.

Myositis Ossificans of the Abdominal Rectus Muscle: Report of a Case

We herein report a rare case of myositis ossificans originating from the abdominal rectus muscle, found in a 38-year-old woman who presented with a left upper abdominal mass. The mass was initially suspected to be a malignant neoplasm because no history of either operation or trauma existed for this patient. Moreover, the location of the mass was unusual and the enhancement patterns of the dynamic magnetic resonance images were similar to that of a malignant tumor. Based on the radiologic findings, a surgical exploration was performed. A well-circumscribed mass, which measured 3.2 x 2 cm, was found in the rectus muscle. Microscopic findings showed a typical zonal pattern with a fibroblastic central zone and a zone of ossification at the periphery. Although abdominal myositis ossificans is extremely rare, it is one of the causes of abdominal mass lesions and can be mistaken for a malignant tumor. Therefore, a thorough knowledge of the evolution of myositis ossificans is necessary and in cases with malignant suggestion on magnetic resonance imaging, like that seen in our case, we suggest that a surgical excision may be necessary for both the diagnosis and treatment.

Florid reactive periostitis of the thumb: a case report and review of the literature

Florid reactive periostitis is a rare benign bone lesion that occurs most often in the phalanges of hands and feet. Histologic evaluation is commonly required to distinguish this benign lesion from clinically indistinguishable malignant and infectious disorders. The lesion is typically self-limiting or cured by local excision; however, in very aggressive cases ray amputation may be indicated. The authors report a case of florid reactive periostitis affecting the thumb with satisfactory outcome and without recurrence at 2-year follow-up.

Myositis ossificans of the hand

We present a case of myositis ossificans of the hand and review the clinical, radiological, and histological presentation, as well as the appropriate therapeutic management.

Fibro-osseous pseudotumor of the digit: a comparison to myositis ossificans by light microscopy and immunohistochemical methods

Fibro-osseous pseudotumor of the digit is an unusual cutaneous process characterized histologically by a fibroblastic proliferation admixed with reactive/metaplastic osteoid formation. The osteoid formation can be florid and immature, mimicking the appearance of malignant osteoid-forming neoplasms. Fibro-osseous pseudotumor of the digit has histologic and clinical features in common with myositis ossificans. This has led many to consider the two to be synonymous. We studied three cases of fibro-osseous pseudotumor, compared to five cases of myositis ossificans, using routine light microscopy and a battery of immunohistochemical stains. Both entities displayed a "zoning" pattern of immature spindled areas admixed with more mature areas having osteoid metaplasia. This was more pronounced in myositis ossificans. In each lesion, the spindle cells stained positively for vimentin and actin. CD34 and Factor VIII highlighted the vasculature. No stromal staining for MAK-6 (cytokeratin) or S-100 was identified. Ki-67, a proliferation marker, showed positive staining of the stromal cells in both lesions, which was strongest in the immature spindled areas. The immunohistochemical and histologic similarities of the lesions support fibro-osseous pseudotumor of the digit being a cutaneous variant of myositis ossificans.

Florid reactive periostitis of the thumb

A case of florid reactive periostitis of the thumb is presented. This is a rare pseudosarcomatous lesion which generally has a benign radiographic appearance, but on histology it may be mistaken for a malignant process. The clinical behaviour may simulate a malignant tumour but after local excision there is very little propensity for recurrence. Local resection is the recommended treatment. Surgeons and pathologists should consider the possibility of florid reactive periostitis before making a diagnosis of sarcoma in the hand.

Florid reactive mesenchymal proliferation

Florid reactive mesenchymal proliferation describes a benign soft tissue tumour found in the hand as well as at other sites. The histological appearance and rapid growth of the lesion may lead to an incorrect diagnosis of malignancy. We describe a case in a 79-year-old lady, unusual because of her age at presentation and long history, and review the literature.

Lesions of juxtacortical origin (surface lesions of bone)

A large variety of tumor and tumor-like conditions have been shown to originate from the surface of bone (Table 1). Most surface lesions are associated with periosteal reaction. The periosteum is a multipotential membrane. Its cellular composition may give rise to a variety of both neoplasms and tumor-like conditions. To avoid misinterpretation, the orthopedist, radiologist, and pathologist should be familiar with the entire spectrum of surface lesions. A better understanding of the natural history and biological behavior at different lesional maturity stages and correlation of the history with the radiographic and pathological findings is essential to establish the correct diagnosis. A history of injury or blunt trauma is very important. A stress fracture may produce a periosteal reaction acd callus that can be difficult to distinguish from osteosarcoma. In this review article, the authors wish to describe and define each term by its anatomy and radiographic features while discussing the entire spectrum of surface lesions. All the illustrative cases in this review article have been proven histologically.

Fibro-osseous pseudotumor of the digits: report of a case with immunohistochemical and ultrastructural studies

A polypoid fibro-osseous nodule arising from the soft tissues of a toe of a 17 yr old man is described. Initial partial excision of the nodule led to a wrong diagnosis of pyogenic granuloma. The mistaken diagnosis was based on finding an extensively ulcerated polypoid nodule with a core of fibrovascular tissue which resembled granulation tissue. The fast growing lesion recurred twice within 4 mths following incomplete excisions. Bony destruction of the distal phalanx was noted radiologically at the second recurrence. The rare lesion is an example of fibro-osseous pseudotumor of the digits, sometimes described as pseudomalignant osseous tumor of the soft tissues. It is curable by complete local resection. The importance of recognizing this lesion lies in its potential to be confused with parosteal or extraskeletal osteosarcoma. The fast growth rate of present case led to a strong clinical suspicion of malignancy. Incomplete excisions resulted in local recurrences rendering more extensive surgery necessary. There was no further recurrence 12 mths after the last excision.

Myositis ossificans with atypical clinical, radiographic, or pathologic findings: a review of 23 cases

Myositis ossificans is a relatively rare, well-defined entity. The 23 cases sent for consultation to two of us (L.V.A. and A.N.) were reviewed. Clinical, radiologic, and microscopic information was reexamined, and special attention was given to features infrequently seen in typical myositis ossificans. Average age at presentation was 23 years, but 1 patient was younger than 2 years, and 2 were younger than 10 years. Due to the uncommon location of 15 lesions and an unusual presentation in 5, the correct diagnosis was not obvious in these cases. A history of trauma was elicited in 8 patients, denied by 7, and was not queried in the remainder. Radiologic studies raised the possibility of a malignant bone-forming tumor in at least three instances; myositis ossificans was originally diagnosed in 6 cases radiologically. In 8 cases, histologic evidence suggested malignancy, including osteosarcoma, either parosteal or extraosseous, in 6. Other diagnoses included epithelioid sarcoma and callus formation. Presentation of these variations from the norm highlights the importance of recognizing the evolution of a nonneoplastic fibro-osseous and cartilaginous entity in which conservative treatment is curative.

Parosteal osteogenic sarcoma of the hand

Osteosarcomas of the tubular bones of the hands and feet are rare tumours and the initial biopsies are frequently misdiagnosed. We report a case of parosteal osteosarcoma arising in the metacarpal of a female patient aged 53 at first presentation. The tumour recurred three times over two decades and eventually metastasized to the lungs. The differential diagnosis includes florid reactive mesenchymal proliferation and bizarre parosteal osteochondromatous proliferations of the tubular bones of the hand.

Pseudomalignant osseous tumor of soft tissue: a case report and review of the literature

Pseudomalignant osseous tumor of soft tissues is a rare tumor of the hand. Histopathologic differentiation of this benign lesion from malignant lesions is difficult because mitotic figures are common in typical cases, but bizarre pleomorphic and hyperchromatic nuclei never occur. Wide excision is adequate in most cases, but ray resection is indicated when this benign lesion recurs after wide excision, invades the vital structures, or causes severe functional impairment. Review of the literature revealed 15 cases of this lesion in the digits of the hand, including our case. Of these 15 cases, misdiagnosis of malignancy in three cases and loss of function in an additional four cases led to ray resection.