Eight (25.8%) patients presented both local and distant disease, with multiple site involvement in seven (22.5%) patients.
Moreover, multiple site involvement can be seen and the reported incidence was 9% in the previous studies [ 2, 7].
In all, 15 (48.3%) patients had locally advanced or recurrent disease only and 16 (54.8%) presented with distant metastatic spread, with multiple site involvement in 22.5%.
Concerning disease extent at study entry, 31% of patients had only locally advanced disease, while 69% had distant disease (lungs, 43%; liver, 14%; lymph nodes, 10%; bones, 2%), with multiple site involvement (more than one metastatic site) in 40%.
However, delayed neck metastasis (DNM) eventually develops in 14 to 48%% of these patients [ 45– 49], which is apt to be accompanied by detrimental features such as extracapsular spread and multiple site involvement.
Furthermore, at study entry, a high proportion of patients had distant metastatic disease (69%) with the commonest site being lungs (43%), however, 14% of the patients had liver involvement, which is considered an unfavourable prognostic factor for response, while more than one-third of the patients had extensive disease with multiple site involvement.
Regarding topography and extension of orofacial swelling, approximately half of the patients had OFG limited to a single labial or facial site, whilst the remaining patients had multiple-site involvement.
Thirty-one patients had single-site involvement and 36 patients had multiple sites involved.
In clinically and radiologically advanced-stage PBL patients having multiple bone site involvement, especially in those with regional lymph node and/or adjacent soft tissue involvement, it may be impossible to distinguish mPBL from SBL.
Secondary involvement of the gastrointestinal tract is extremely common, usually from direct extension from involved mesenteric or retroperitoneal lymph nodes and consequently multiple sites of involvement do occur.
Most patients have multiple sites of involvement at presentation.
