Benign soft tissue lesions that may mimic malignancy

Cat-scratch disease mimicking soft tissue sarcoma in a pediatric patient

Cat scratch disease, first described in France in the 1930s, is a benign infectious disease with often atypical presentation. Its clinical symptoms and radiologic features can overlap with those of a sarcoma. Here we present the case of a 12-year-old female with cat-scratch disease that was initially misdiagnosed as a soft tissue sarcoma of the elbow. The patient was then successfully treated with an antibiotic course. Our case emphasizes the importance of early consultation by a specialized multidisciplinary team given the lack of specificity and overlap of presentation among benign and malignant masses.

Elshinawy W, Mohamed Ahmed E, A. Raafat M, Husien Abdo W, A. Abdel Wahab M, E. Elimam S, Alsagheer Alhewy M. Masson's Tumor as an Uncommon Cause of Neck Mass: A Case Presentation

BACKGROUND

Masson's tumor, commonly referred to as intravascular papillary endothelial hyperplasia (IPEH), is an uncommon growth of endothelial cells within a vessel wall that is frequently assumed to indicate an abnormal resolution of thrombosis. IPEH is most typically found in the extremities however it is rare for IPEH to appear as a neck tumor. The issue with IPEH is that it could clinically, radiologically, and pathologically imitate some malignant neoplasms such as angiosarcomas creating a diagnostic challenge.

CASE REPORT

We describe a 21-year-old male patient who presented with right anterolateral neck swelling for 12 months. Ultrasound revealed a 9.0 × 8.0 cm well-defined echogenic hyper-vascular lesion. The contrast computed tomography (CT) scan of the neck revealed an oval, well-defined subcutaneous mass, measuring 9 × 4.5 cm, situated over and separable from the right sternocleidomastoid muscle with no significant enhancement in the post-contract study. T1-weighted and T2-weighted MRI revealed a 10 × 9 × 7 cm well-defined subcutaneous lobulated lesion superficial to the sternocleidomastoid expanding upward to the Rt. side of the cheek and below to the suprasternal region, eliciting an intermediate signal in T1 and a heterogenous bright signal (mostly fluid) in T2 with low signal foci within the mass. The decision had been reached to entirely excise the lesion surgically with safety margins for histological evaluation. Histological examination indicated thrombosed variable-sized ectatic vascular spaces with papillary formations related to the thrombus, covered with a single layer of flat endothelium, and no features suggestive of malignancy. There was no recurrence at 18 months follow-up post-surgery.

CONCLUSION

Masson's tumor is a benign intravascular disease with an unclear origin and no confirmed inheritance pattern. Presentation of Masson's tumor as a neck mass is incredibly uncommon. Masson's tumor lacks a distinct or distinguishing clinical and radiological appearance. Histopathologic examination is the sole definitive way for diagnosing the disease and the only tool for distinguishing it from angiosarcoma. Surgical excision is the best treatment for IPEH. Recurrence is extremely rare.

Epithelioid and spindle rhabdomyosarcoma with TFCP2 rearrangement in abdominal wall: a distinctive entity with poor prognosis

BACKGROUND

Epithelioid and spindle rhabdomyosarcoma (ES-RMS) with TFCP2 rearrangement is a recently discovered rare variant of rhabdomyosarcoma composed of epithelioid and spindle cells, because it shows extraordinarily adverse prognosis and is easily misdiagnosed as other epithelioid or spindle cell tumors.

METHODS

A rare case of ES-RMS with TFCP2 rearrangement was presented and English literatures in Pubmed online up to 01 July 2022 were gathered by two authors for a systematic review according to the inclusion and exclusion criteria.

CASE PRESENTATION/RESULTS

We report a case of ES-RMS in an early 30s-years-old female, the neoplastic cells are remarkably immunoreactive with CK(AE1/AE3), and partially with ALK protein. Unexpectedly, the tumor shows TFCP2 rearrangement with coexistence of increased copy numbers of EWSR1 and ROS1 gene and MET gene mutation. Besides, Next-generation sequencing for genetic mutational profiling revealed frequent MET exon14 mutations in chromosome 7, most of which are C > T nonsynonymous SNV, and exon42 of ROS1 in chromosome 6 showed frequent G > T mutation up to 57.54%. In addition, neither MyoD1 mutation nor gene fusions were detected. Moreover, the patient shows high tumor mutational burden (TMB) up to 14.11 counts/Mb. Finally, as many cases of ES-RMS including our case had local progression or metastasis, we find, similar to epithelioid rhabdomyosarcoma (median survival time is 10 month), ES-RMS shows a more aggressive behavior and adverse prognosis (median survival time is 17 month) than spindle cell/sclerosing rhabdomyosarcoma (median survival time is 65 month) according previous studies.

CONCLUSIONS

ES-RMS with TFCP2 rearrangement is a rare malignant tumor and easily confused with other epithelioid or spindle cell tumors, it may harbor additional gene alteration in addition to TFCP2 rearrangement, such as MET mutation, increased copy numbers of EWSR1 and ROS1 gene, high TMB. Most importantly, it may show very poor outcome with extensive metastasis.

Rare Pseudosarcomatous Lesions Posing Diagnostic Challenges: Histopathologic Examination as a Dominant Tool Preventing Misdiagnosis of Proliferative Fasciitis

Proliferative fasciitis is an extremely rare benign myofibroblastic proliferation that typically presents as a rapidly growing subcutaneous mass. Precise histopathological interpretation is required to obtain a proper diagnosis. Due to a symptomatology overlap, discrimination from soft tissue sarcomas is crucial in the prevention of unnecessary excessive treatment that could be potentially harmful to the patients. Here, we present a rare case of atypical localization of proliferative fasciitis. The lesion was predominantly localized in the groin with the invasion of the scrotum and clinically mimicked soft tissue sarcoma. However, according to a proper histopathologic analysis, the diagnosis of proliferative fasciitis was concluded. With a large number of pseudosarcomatous lesions, there is a rising urge to introduce these rare but benign processes to physicians in order to prevent misdiagnosing patients.

Intra-articular Myxoma Arising from the Scapholunate Ligament: A Rare Cause of Dorsal Wrist Swelling

The differential diagnosis of a dorsal wrist swelling includes ganglion, lipoma, cutaneous tumors, and benign peripheral nerve sheath tumors, with ganglions being the most common. We present the case of a myxoma arising from the dorsal scapholunate ligament mimicking a dorsal wrist ganglion. Volar wrist joint myxomas have been previously reported, but this is the first report of a myxoma arising from the dorsal side of the wrist joint.

A Case Report of the Intravascular Fasciitis of a Neck Vein Mimicking Intravascular Tumorous Conditions

Intravascular fasciitis is a rare variant of nodular fasciitis, which can be easily misdiagnosed as a tumorous condition. We had a patient with an intravenous mass of a neck vein, and surgical excision was successful. Although all preoperative imaging studies and intraoperative pathologic reports suggested certain tumorous conditions as differential diagnosis results, the final diagnosis confirmed that it was an intravascular fasciitis based on its fibromixoid tissues with the proliferation of spindle cells and positive immunohistochemical staining for smooth muscle actin. Unless a physician has an insight of the disease or a suspicion to initiate running differential markers, it may be confused with other intravascular lesions and cause unnecessary radical surgery. Here we report our experience with a patient having this rare vascular disease.

Nonepithelial Tumors and Tumor-like Lesions of the Skin and Subcutis in Children

This overview of mesenchymal tumors presenting in the skin and/or subcutis in children brings together the range of neoplasms and hamartomas which are seen in this age-group. It is not surprising from the perspective of the pediatric or general surgical pathologist that vascular anomalies, including true neoplasms and vascular malformations, are the common phenotypic category. Since there is considerable morphologic overlap among these lesions, clinicopathologic correlation may be more important than for many of the other mesenchymal tumors. The skin and subcutis are the most common sites of clinical presentation for the infantile myofibroma which is the most common of fibrous mesenchymal tumors in children. Several of the other mesenchymal tumors are more common adults-like dermatofibrosarcoma protuberans, but nonetheless have an important presence in children, even as a congenital neoplasm. A lipomatous tumor in a young child should be considered as a possible manifestation of an overgrowth syndrome.

Proliferative Fasciitis in Childhood: A Review of Clinical Data Apropos of a Case

Proliferative Fasciitis (PF) is a benign lesion with histologic and clinical features overlapping with those of malignant soft tissue tumours. Its occurrence in children is considered very rare. We present a case of PF appearing as a painful, red, gradually increasing in size lesion, during a period of a few weeks, on the finger of a five-year-old boy compromising the dermis and subcutaneous tissue. We were able to locate literature on 20 paediatric PF cases, which we review. Only five of these focus on the clinical data, the rest describing mainly histological findings. It is the first reported paediatric case appearing on the finger.

Delayed phlegmon with gallstone fragments masquerading as soft tissue sarcoma

Complications from lost gallstones after cholecystectomy are rare but varied from simple perihepatic abscess to empyema and expectoration of gallstones. Gallstone complications have been reported in nearly every organ system, although reports of malignant masquerade of retained gallstones are few. We present the case of an 87-year-old woman with a flank soft tissue tumor 4 years after laparoscopic cholecystectomy. The initial clinical, radiographic and biopsy findings were consistent with soft tissue sarcoma (STS), but careful review of her case in multidisciplinary conference raised the suspicion for retained gallstones rather than STS. The patient was treated with incisional biopsy/drainage of the mass, and gallstones were retrieved. The patient recovered completely without an extensive resectional procedure, emphasizing the importance of multidisciplinary sarcoma care to optimize outcomes for potential sarcoma patients.