PBL is a rare and aggressive type of NHL that is strongly associated with HIV infection and often occurs within the oral cavity. HIV-related lymphomas are frequently associated with EBV. Dual infection with EBV and HHV8 has been demonstrated in PBL. Cases of PBL occurring in immunocompetent patients have been documented and increasingly described, particularly in HIV-negative patients.
The median age of PBL at presentation is around 50 years old, with a male predominance of 5.7:1. Our patient was a young man who presented in his 2nd decade of life, defying the average statistics, with multiple lesions in the skin and had systemic involvement at diagnosis. He was immunocompetent and HIV-negative. Also, EBV and HHV8 were negative with no previous relevant medical history or immunosuppression.
While there have been reports of PBL in HIV-negative patients and at extraoral sites, accurate diagnosis of such cases is not easy as PBL may be poorly recognized by pathologists, which is partly attributable to its relatively rare occurrence, unusual immunophenotype, its heterogeneous presentation, and similarity to different malignancies based on morphology and even immunophenotypic expression.
Immunophenotyping is an important adjunct in differentiating PBL from other neoplasms. Differential diagnoses of PBLs based on a morphologic basis include poorly differentiated carcinoma, anaplastic large cell lymphoma, immunoblastic variant of diffuse large B-cell lymphoma including primary cutaneous diffuse large B-cell lymphoma, anaplastic plasmacytoma, myeloid sarcoma, and metastatic melanoma. Carcinomas can be differentiated from PBLs based on positivity for cytokeratin. Anaplastic large cell lymphomas are negative for CD38 or CD138; PBLs are negative for CD20, while immunoblastic variants of diffuse large B-cell lymphoma are negative for CD138 and positive for CD20/PAX5. Myeloperoxidase and S-100 negativity rule out myeloid sarcoma and metastatic melanoma, respectively.
Clinical correlation is occasionally required in the differential diagnosis of PBL and buy methysergide cell myeloma with plasmablastic features because of their nearly identical immunophenotypic profiles. PBL is composed almost entirely of blasts, whereas plasmacytoma typically consists of mature plasma cells, and in addition, the extremely high proliferation rate of PBL with many mitotic figures are unusual for plasmacytoma. Cytoplasmic Igs are not detected in approximately 50% of PBL cases and, thus, the negative staining for kappa and lambda light chains do not preclude the diagnosis of PBL.
To date, 26 cases of PBL presenting in the skin have been reported; 14 cases were HIV positive, eight cases were post-transplantation, one patient had an autoimmune disorder, while three patients were immunocompetent without any history of immunosuppression similar to our patient, but in contrast to our patient who was young (20 years old). These three patients consisted of an 80-year-old man, an 86-year-old woman, and a 62-year-old woman.
Several adverse prognostic factors have been identified, including HIV-negativity, MYC gene rearrangement, and high-risk international prognostic index. The outcome with available therapy is poor, with median survival of <1 year; some data suggest a better outcome of PBL if consolidation with autologous hematopoietic cell transplantation is used in a first-line setting. Our patient\'s condition rapidly deteriorated and he died 1 week after diagnosis despite being started empirically on bortezomib together with dexamethasone before final diagnosis. This in contrast to recently published cases which showed that bortezomib has shown promising results in PBL.
Dermatological examination revealed multiple hyperkeratotic papules and filiform spine over her trunk and extremities where lesions presented along Blaschko\’s line in the form of a systematized linear epidermal nevus (Figures 1A–1F). On closer examination, the hyperkeratotic lines were found to be composed of small filiform keratotic plugs. At their base, the plugs had a pitted keratotic papule similar to a comedo nevus. On her left lower extremity, the more serious lesions had arisen in a thornlike fashion vertically (Figures 1D–1F). The thornlike projections with larger plugs were very closely grouped and some of them coalesced into hyperkeratotic verrucous plaques. Those plugs could be extracted and some pits remained. Both palms and soles had similar lesions and the soles were highly hyperkeratotic. At the left pretibial site, a demarcated circular ulcer 2.5 cm in diameter was found. The head and face were spared. The systemic examination, including chest X-ray, electrocardiogram, echocardiogram, and ultrasonogram of the abdomen, was normal.