BACKGROUND: Papillary intralymphatic angioendothelioma (PILA) is an exceptionally rare metastasizing soft tissue tumor. It tends to arise in the subcutaneous tissues of distal extremities in children. Only four intraosseous PILA cases have been reported until now in English language literature.
METHODS: We present a case of PILA arising in the distal femoral epiphysis of a 50-year-old female patient. It started as a relentless pain in her left knee. A plain radiography revealed a radiolucent area in the left internal femoral condyle. Computerized tomography revealed a 1-cm lytic lesion with a sclerotic rim. Magnetic resonance images showed a significant bone marrow edema signal focused on a 1-cm subchondral lesion suggestive of an intraarticular osteoid osteoma. Histologically, the tumor contained vascular channels covered by a single endothelial layer with intraluminal papillary endothelial structures lined with hobnail cells. Immunohistochemically, the cells were positive for ERG, CD31, and D2-40. The tumor underwent cryoablation and 6 months later, after local recurrence or tumor persistence, a wide tumor resection was referred. After 7 years of follow-up, the patient displayed neither local recurrence nor distant metastases.
CONCLUSIONS: Primary intraosseous PILAs are exceedingly rare tumors that should be considered in the differential diagnosis of vascular bone tumors.

The term \"hemangioendothelioma\" is used for endothelial neoplasms of intermediate malignancy and describes a group of rare neoplasms having biologic behavior falling in between that of the benign hemangiomas and fully malignant angiosarcomas. The hemangioendotheliomas fall into several specific, clinicopathologically and genetically distinct entities, specifically epithelioid hemangioendothelioma, kaposiform hemangioendothelioma, papillary intralymphatic angioendothelioma and retiform hemangioendothelioma (hobnailed hemangioendothelioma), pseudomyogenic hemangioendothelioma, composite hemangioendothelioma, and YAP1::TFE3-fused hemangioendothelioma. The clinical, morphologic, immunohistochemical, and genetic features, and the differential diagnosis of each of these rare entities are discussed in this review.

Published data regarding lymphangiomatous cysts of the adrenal glands (also known as adrenal cystic lymphangiomas) are limited to case reports and a few small case series. We analyzed the clinicopathologic features and histomorphologic spectrum of 37 cases of adrenal cystic lymphangiomatous lesions. There were 26 females and 11 males ranging from 12 to 67 years old (median, 34 years). Twenty two lesions (59.5%) were diagnosed incidentally on imaging studies for unrelated causes, while 15 cases (40.5%) were symptomatic: 8 patients presented with abdominal or flank pain and 7 patients presented with arterial hypertension. Clinically, 4 lesions (10.8%) were reported to have concurrent hormonal hypersecretion. Follow-up data were available for 23 patients (62.2%), ranging from 6 to 156 months (median, 52 mo). One of the 22 patients showed local recurrence at 12 months after partial adrenalectomy. The median size of the adrenal lymphangiomatous cysts was 4.5 cm (range, 1.5 to 10 cm). Based on the histopathologic findings these lesions were grouped into three, morphologically distinct types: typical multicystic lymphatic malformation (n = 16), typical unilocular lymphangiomatous cyst (n = 14) and lymphangiomatous cyst with papillary endothelial proliferation (n = 7). The median patient age of the first group was significantly higher than that of the other groups and calcifications in these cysts were more common than in the other two groups. The unilocular lymphangiomatous cysts were more frequently associated with a history of previous intra-abdominal surgical procedures and/or inflammatory processes than the other two groups. Cysts with papillary endothelial proliferation were significantly larger than other cysts and shared some microscopic features with a vascular neoplasm known as papillary intralymphatic angioendothelioma (PILA). In conclusion, adrenal lymphangiomatous cysts are usually asymptomatic, incidentally diagnosed lesions with a female predominance. They may imitate other adrenal tumors, both radiologically and clinically. Despite being non-functioning lesions, they should be considered as a possible cause of pseudopheochromocytoma. Although most adrenal lymphangiomatous cysts seem to be non-neoplastic, vascular abnormalities (malformations or lymphangiectasias), those with papillary endothelial proliferations may represent true neoplastic lesions.

BACKGROUND: Papillary intralymphatic angioendothelioma (PILA) is a locally aggressive, rarely metastasizing vascular tumor, generally occurring in the soft tissues, with less than 40 cases described in the literature and only three cases reported in bone.
METHODS: We describe the case of a 51-year-old male with an intraosseous PILA of the proximal edge of his left clavicle and two other lesions evident on imaging. The patient was treated with marginal resection of the clavicle lesion but was lost to follow-up 1 month after surgery.
CONCLUSIONS: PILA can also occur in bone, albeit very rarely, and has to be considered in the differential diagnosis of vascular bone tumors.