Sabato 27 ottobre 2012 - Pacini Editore

RElaziONi
Infezioni batteriche e linfomi extranodali
M. Ponzoni
U.O Anatomia Patologica, Area Diagnostica di Emopatologia, Istituto
Scientifico Ospedale San Raffaele, Milano
Il rapporto tra agenti infettivi e sviluppo di processi linfoproliferativi,
tradizionalmente rappresentato dai virus, si è
arricchito negli ultimi 25-30 anni grazie al contributo offerto
dai batteri. Tale legame è particolarmente evidente per le forme
extranodali a basso grado, soprattutto a istotipo MALT.
Al di là del ruolo storicamente rappresentato dal rapporto
patogenetico tra infezione da Helicobacter pylori e il linfoma
di tipo MALT gastrico, altri agenti infettivi di tipo batterico
sono stati variabilmente associati ad altri tipi di linfomi, con
livelli differenti di evidenza di tale associazione. Nel corso
della presentazione verrà effettuata un’analisi critica dei vari
agenti proposti e delle più recenti acquisizioni sul piano
patogenetico-terapeutico in tale ambito.
Pleuropulmonary lymphoproliferative diseases
M. Chilosi
Anatomia Patologica, Department of Pathology, University of Verona
Pulmonary presentations of lymphoproliferative diseases are
rare, accounting for less than 4% of lymphomas primarily
involving extranodal sites, and can occur in three different
ways: First, as primary lymphomas arising within the lung parenchyma;
second, as secondary spreads from the circulation;
third, as secondary site of involvement from neighbouring
sites (e.g. from mediastinal lymph nodes or thymus). These
three presentations have different diagnostic, prognostic and
therapeutic implications 1 2 . Precise pathologic diagnosis and
molecular characterisation is required in all cases, following
W.H.O. classification criteria. Radiologic features include
pulmonary consolidation, solid pulmonary opacities, hilar
adenopathy or pleural effusion. Principles of treatment vary
with the different histology.
Three broad categories of lymphoma of the lung require recognition:
the most common histologic subtype is represented
by low grade mucosa-associated lymphoid tissue (MALT)
lymphoma, often in the past considered as a pseudotumour
because of its long indolent natural history. In primary pulmonary
MALT lymphomas, cytogenetic abnormalities are
common (75%) and heterogeneous, encompassing API2-
MALT1 and IGH-MALT1, which are mutually exclusive [3,4].
Morphologically, lymphoma cells are similar to normal marginal-zone
cells, exhibiting a spectrum of cytological features
(small-round cells, centrocyte-like cells, monocytoid cells),
characterised by small and irregular nuclei, inconspicuous nucleoli,
and abundant clear cytoplasm. Neoplastic lymphocytes
typically accumulate around non-neoplastic lymphoid follicles,
forming poorly defined sheets of cells at the periphery
of the mantle zones, extending into the lung parenchyma. The
presence of reactive follicles, that can be particularly abun-
Venerdi, 26 ottobre 2012
Sala Michelangelo – 10.30-12.30
Linfomi extranodali problematiche diagnositche
Moderatori: Simonetta Di Lollo (Firenze), Fabio Facchetti (Vicenza)
235
dant and are presumably pre-existing the lymphoma development,
can pose diagnostic problems at morphological and also
immunophenotypical analysis. In rare instances, large B-cell
lymphoma can present primarily in the lung, often associated
to low-grade MALT lymphoma. A variety of uncommon
primary lymphomas include lymphomatoid granulomatosis,
nasal-type T-cell lymphoma, intravascular B-cell lymphomas,
anaplastic CD30+ large cell lymphoma, classic-type Hodgkin’s
lymphoma, and others.
Lymphomatoid granulomatosis (LYG)[5]. This term defines
an angiocentric and angiodestructive lymphoproliferative
disease involving extranodal sites. The term LYG includes
a group of related lesions characterised by the infiltration of
pulmonary parenchyma by an heterogeneous cell population
composed of a large number of T-lymphocytes, a variable
proportion of large EBV-infected B-cells, (as defined by
expression of B-cell related antigens CD20 and CD79a,
and EBV markers such as LMP-1 and EBER). LYG lesions
are heterogeneous, and have been graded depending on the
proportion of neoplastic B cells, the degree of lymphocytic
atypia, and the heterogeneity of the infiltrate, distinguishing
three grades characterised by varying proliferation index and
prognostic differences. The grade 3 forms can be considered
as diffuse large B-cell lymphomas, with features of T-cell rich
DLBCL. LYG needs to be distinguished from other diseases
characterised by zonal necrosis and prominent angioinvasion,
including extranodal NK/T (nasal-type) T-cell lymphoma, and
Wegener’s granulomatosis.
Nasal-type T/NK lymphomas when occurring in the lung can
present many similarities with LYG, including angioinvasion,
expression of markers of EBV infection, necrosis, immune
disturbances and a rich T-cell infiltrate exhibiting cytotoxic
immunophenotype, as defined by the expression of CD8, TIA-
1, granzyme-B, and perforin [6].
Hodgkin’s lymphoma (HL). Primary pulmonary HL is a rare,
but distinct disease, involving the upper lobes and presenting
as a solitary mass, as multinodular, or more rarely as endobronchial.
The involvement of mediastinal lymph nodes must
be excluded to define the lymphoma as truly primary. The
differential diagnosis includes a variety of lung diseases, and
a surgical biopsy is needed. Neoplastic nodules are formed by
an heterogeneous cell population, including many inflammatory
cells (macrophages, T lymphocytes, granulocytes) and
isolated atypical cells characterised by the cytological features
and immunophenotype of Reed-Sternberg/Hodgkin’s cells.
Various modifications can be observed in the parenchyma
adjacent to the neoplastic nodules of Hodgkin’s lymphoma,
including focal organising pneumonia, endoalveolar accumulations
of foamy macrophages and interstitial lymphoid
infiltration.
Secondary lymphomas. Secondary lung localization by lymphomas
occurs with relative frequency (up to 20.5% at autopsy),
with different patterns of infiltration (peribronchial/
perivascular, nodular, alveolar, interstitial, pleural, endobronchial).
The lymphangitic pattern is frequent in B-cell lympho-