Papillary Intralymphatic Angioendothelioma (PILA): Definition and Management
PILA is a rare, low-grade vascular tumor with lymphatic phenotype that primarily affects the skin and soft tissues of children and young adults, requiring complete surgical excision with clear margins as the definitive treatment.
What is PILA?
PILA, previously known as Dabska tumor, is a rarely metastasizing lymphatic vascular neoplasm originally misclassified as malignant but now recognized for its borderline behavior 1. The tumor is characterized by:
- Distinctive intravascular growth of well-differentiated endothelial cells with papillary proliferations
- Hobnail-like endothelial cells lining slit-like vascular channels
- Lymphatic phenotype confirmed by positive VEGFR-3 staining
- Minimal cytologic atypia with rare to absent mitotic activity 1
The tumor most commonly presents in the extremities (buttocks, thigh, hand), though rare visceral cases (spleen) have been reported 2, 3, 4. It typically manifests as a soft-tissue mass that may be initially misdiagnosed as a benign vascular lesion 3.
Management Algorithm
Primary Treatment: Surgical Excision
Complete surgical excision with negative margins (R0 resection) is the cornerstone of treatment 5, 6. The surgical approach should include:
- Wide local excision with adequate margins to achieve R0 resection
- Re-excision if initial margins are positive - this is the standard approach when PILA is discovered as an unexpected pathology after initial excision 5
- Consider sentinel lymph node biopsy during re-excision, particularly given the tumor's lymphatic phenotype and potential for metastasis 5
Reconstruction
- Skin grafting may be necessary after wide excision, particularly for larger lesions 5
- For extensive tumors where limb preservation is challenging, consider the principles used for soft tissue sarcomas, though PILA is less aggressive
Role of Adjuvant Therapy
No evidence supports routine use of radiotherapy or chemotherapy for PILA. The tumor's indolent nature and excellent outcomes with surgery alone make adjuvant treatment unnecessary in most cases. The available literature shows no recurrences or metastases in patients with adequate surgical excision during follow-ups ranging from 1 to 17 years 1.
Critical Follow-Up Requirements
Long-term surveillance is mandatory despite the generally favorable prognosis, because PILA has documented potential for:
- Local recurrence if margins are inadequate 3, 4
- Rare metastatic spread (though uncommon with proper excision) 6
- Local invasiveness into surrounding structures 3
Surveillance Protocol:
- Frequent clinical examination of the surgical site and regional lymph nodes 5
- Annual follow-up at minimum, with longer intervals as time progresses
- Immediate evaluation of any new skin lesions or lymphadenopathy 5
Common Pitfalls to Avoid
Misdiagnosis as benign vascular lesion: PILA often mimics hemangioma, lymphangioma, or hamartoma on imaging 4, 7. Always obtain histopathological confirmation with immunohistochemistry (D2-40, ERG, CD31, CD34, VEGFR-3 positive) 3.
Inadequate initial excision: When PILA is discovered unexpectedly after excision of a presumed benign lesion, do not simply observe - proceed with re-excision to achieve clear margins 5.
Failure to consider lymph node involvement: Given the lymphatic phenotype, sentinel lymph node biopsy should be considered, particularly for larger or recurrent tumors 5.
Premature discontinuation of follow-up: The borderline nature requires lifelong surveillance, as late recurrences are possible 3, 6.