Superficial Angiomyxomas Frequently Demonstrate Loss of Protein Kinase A Regulatory Subunit 1 Alpha Expression: Immunohistochemical Analysis of 29 Cases and Cutaneous Myxoid Neoplasms With Histopathologic Overlap

Update on immunohistochemistry in bone and soft tissue tumors: Cost-effectively replacing molecular testing with immunohistochemistry

Soft tissue tumors form part of a challenging domain in diagnostic pathology owing to their comparative rarity, astonishing histologic diversity, and overlap between entities. Many of these tumors are now known to be defined by highly recurrent, or, in some instances, unique molecular alterations. Insights from gene profiling continue to elucidate the wider molecular landscape of soft tissue tumors; many of these advances have been co-opted by immunohistochemistry (IHC) for diagnostic applications. There now exists a multitude of antibodies serving as surrogate markers of recurrent gene fusions, amplifications, and point mutations, which, in certain settings, can replace the need for more resource and time-intensive cytogenetic and molecular genetic analyses. IHC presents many advantages including rapid turnaround time, cost-effectiveness, and interpretative reproducibility. A sensible application of these immunohistochemical markers complemented by a working knowledge of the molecular pathogenesis of bone and soft tissue tumors permits accurate diagnosis in the majority of cases. In this review, we will outline some of these biomarkers while emphasizing molecular correlates and highlighting interpretative challenges and pitfalls.

Concurrent PTEN and PDGFRB Alterations Characterize Storiform Collagenoma

Storiform collagenoma is a rare mesenchymal skin tumor that is composed of thickened collagen bundles arranged in a characteristic storiform pattern with a relatively hypocellular CD34-positive spindle cell component. Storiform collagenoma is most often sporadic, but multiple lesions can occur in Cowden syndrome, which is characterized by germline alterations in PTEN (phosphatase and tensin homolog) on chromosome 10. Here, we investigated the molecular pathogenesis of storiform collagenoma using a targeted next-generation DNA sequencing platform, including 5 sporadic cases and one case associated with Cowden syndrome. Recurrent PTEN alterations were identified in all cases, with biallelic PTEN inactivation observed in the case associated with Cowden syndrome and one sporadic case. Unexpectedly, we also identified recurrent activating mutations in the platelet-derived growth factor receptor beta ( PDGFRB ) gene. This included a missense substitution in the D5 Ig-like domain of PDGFRB in the Cowden syndrome-associated case. In addition, we report missense alterations in the juxtamembrane domain of PDGFRB in 4 of 5 (80%) sporadic cases, including mutations that have been previously described in sporadic myofibroma and myopericytoma. Therefore, we confirm the neoplastic nature of storiform collagenoma, we expand the spectrum of reported PDGFRB alterations in mesenchymal tumors and we suggest a possible collaborative role for PTEN and PDGFRB in the pathogenesis of storiform collagenoma.

Angiomyxoma of the Breast: A Clinicopathologic Analysis of 40 Cases

Superficial angiomyxoma is an uncommon benign mesenchymal neoplasm that usually arises in dermis/subcutis of the extremities or trunk. Some tumors are associated with Carney complex. When arising in breast, these tumors are not well-recognized, mainly due to a lack of uniform nomenclature in the literature. This study therefore aims to improve recognition of angiomyxomas of the breast region. Forty cases were identified: demographics, presence of Carney complex, imaging and histologic features, PRKAR1A expression, and outcomes were evaluated. There were 22 female and 18 male patients (median age 40 years, range: 14 to 72). Most tumors presented as slowly-growing masses (77%). All but one were solitary, and median size was 1.5 cm. Tumors were superficial (dermal/subcutaneous) in 52.5% and deep/parenchymal in 47.5%. Nine involved the nipple-areola complex. All showed characteristic features of superficial angiomyxoma: poorly circumscribed, hypocellular, myxoid neoplasms with lobulated (55%) or infiltrative (45%) architecture, bland spindled fibroblasts, prominent thin-walled vessels, and admixed neutrophils. Tumors involving the nipple-areola complex infiltrated through areolar smooth muscle, and deep/parenchymal tumors showed entrapment of lobules mimicking myxoid fibroadenoma. Mitoses were typically absent, as was significant atypia. Cystic change was common. Two-thirds showed loss of PRKAR1A expression by immunohistochemistry. Two patients had Carney complex (7%). Recurrence after incomplete excision occurred in 1 patient. Angiomyxoma of breast may arise at superficial, nipple-areola or deep/parenchymal locations, where it can be difficult to recognize classic histologic features. Loss of expression of PRKAR1A is not invariable, but may be a helpful diagnostic clue. Recognizing angiomyxoma is important for 2 reasons: first, the recurrence rate is low and therefore wide excision is not essential, and second, it may allow detection of Carney complex in some patients.

A rare case of solitary intraoral superficial angiomyxoma arising in the soft palate

Superficial angiomyxomas are myxoid mesenchymal tumors, and intraoral superficial angiomyxoma is extremely rare. This paper reports a novel case of a 41-year-old Japanese male patient with a 32 × 22 mm superficial angiomyxoma in the right soft palate. Tumor resection was performed and a polyglycolic acid sheet was attached. Over a 28-month follow-up, there was no evidence of disease recurrence. This paper also reviewed 11 cases of intraoral superficial angiomyxomas reported in previous literature. The condition was more common among middle-aged men. Surgical resection was the most common treatment, and local recurrence was observed in only one case.

Pediatric Vulvar Superficial Angiomyxoma: A Case Report With Clinical, Radiological, and Anatomopathological Characterization and a Comprehensive Review of the Literature

Superficial angiomyxoma is characterized as a benign, slow-growing vascular cutaneous myxoma. A 6-year-old Arab girl with no medical history presented with a vulvar tumor located on the left labia majora. The lesion was present since birth, but it had significantly increased over the last 6 months. She did not have any associated symptoms. Physical examination revealed an exophytic tumor of the left labia majora, which measured 5 cm in its major axis. Doppler ultrasound study showed a mass with abundant arterial and venous vascularization, and magnetic resonance imaging showed a highly vascular contrast-enhanced mass with well-delimited margins, which depended on the labia majora. A macroscopically complete resection was performed, achieving a tension-free primary closure. Histologically, the lesion was characterized as a well-demarcated superficial tumor with thin-walled vessels and myxoid stroma, S100 (−), CD34 (+), vimentin (+), and actin (+). The final histopathological diagnosis was superficial angiomyxoma. The literature review of this entity in the pediatric population shows a predominance of this lesion in the vulvar location. Local recurrence has been described. Loss of PRKAR1A expression may be involved in the pathogenesis of superficial angiomyxoma.