|
LINKS
| |
Scheda a cura di Marco Chilosi (GYM)
CLASSIFICAZIONE
WHO
Classificazione "istogenetica"
di
Muller-Hermelink
Tipo
A Timoma Midollare
Nel timoma tipo A le cellule sono prevalentemente fusate.
L'espressione di citocheratine ad alto peso (CK 5, CK6 e CK14) è elevata e sono
scarsi o assenti i linfociti T immaturi (CD1a e TdT+).
Caso 1.
Timoma tipo A (midollare, spindle-cell thymoma).
I
linfociti sono prevalentemente maturi (CD3+, CD1a-) e localizzati esternamente,
negli spazi perivascolari. Con CD1a si identificano sparse cellule dendritiche
(tipo Langerhans CD1a++)
La
citocheratina 34bE12 e la CK14 sono intensamente
espresse nella totalità delle cellule epiteliali neoplastiche
- Caso 2.
-
Caso 2.
Timoma tipo-A
-
EE:
cellule epiteliali prevalentemente fusate, con espressione elevata di
cheratine 34bE12 e CK14
-
°°°°°°°
Am J Surg Pathol 1984 Apr;8(4):309-18
- Immunohistochemical analysis of thymoma. Evidence for
medullary origin of epithelial cells.
Chilosi M, Iannucci AM, Pizzolo G, Menestrina F, Fiore-Donati L, Janossy G.
The histologic organization of lymphoid and nonlymphoid (epithelial and
interdigitating) cells in a thymoma has been compared to that of the normal
thymus. Enzyme and immunohistochemical methods were applied, using both
conventional antisera (to cytokeratin) and monoclonal antibodies (to
epithelial cells, HLA-DR and lymphoid subsets). Throughout the tumor, the
epithelial cells shared phenotypical similarities with the epithelial cells of
thymic medulla (RFD-4 positive, cytokeratin strongly positive, and HLA-DR
essentially negative). On the other hand, the lymphoid cells were
heterogeneous in phenotype and distribution, and "mimicked" the
distribution seen in the normal infant thymus. Immature thymocytes of cortical
type (TdT+, OKT6+, OKT3-) were predominant in the areas with moderate
lymphocytic infiltration (ML). Mature T-lymphocytes (TdT-, OKT6-, OKT3+) were
found mainly in areas with scanty lymphocytes (SL) together with an additional
population of HLA-DR positive interdigitating and HLA-DR+, OKT6+ Langerhans'-type
cells. These findings indicate that in thymoma tissue, the lymphoid elements
of cortical type are apparently surrounded by an inappropriate (medullary)
epithelium.
|
Il
timoma A (a cellule fusate) è clinicamente poco aggressivo, ma esistono
segnalazioni di potenziale evoluzione in forme maligne. |
Am J Surg Pathol 1999 Jun;23(6):691-700
Spindle
cell thymic carcinoma: clinicopathologic and immunohistochemical study of a
distinctive variant of primary thymic epithelial neoplasm.
Suster S, Moran CA.
Arkadi M. Rywlin Department of Pathology and Laboratory Medicine, Mount Sinai
Medical Center and University of Miami School of Medicine, Florida, USA.
We report 16 cases of a distinctive variant of primary thymic epithelial
neoplasm characterized by prominent spindling of the tumor cells. The patients
were seven women and nine men aged 23 to 82 years (mean, 54 years). The lesions
presented as anterior mediastinal masses without clinical or radiographic
evidence of tumor elsewhere. Most patients had chest pain, dyspnea, and cough;
in five patients, the tumors were asymptomatic and were discovered on routine
clinical examination. Grossly, the lesions were firm, well-circumscribed, and
locally infiltrative, and had a firm cut surface with foci of hemorrhage,
necrosis, and cystic changes. Most of the tumors were treated by complete
surgical excision. Histologically, they were characterized by a spindle cell
proliferation showing varying degrees of atypia and mitotic activity. In 12
cases, transitions could be seen with areas that showed the features of
conventional spindle cell thymoma. In two cases, areas showing features of
poorly differentiated (lymphoepitheliomalike) carcinoma and anaplastic carcinoma
could also be observed. Immunohistochemical studies in 10 cases showed strong
positivity of the spindle tumor cells for CAM5.2 cytokeratin, and negative
staining for a panel of antibodies including epithelial membrane antigen,
carcinoembryonic antigen, actin, desmin, vimentin, S-100 protein, HMB45, CD34,
CD5, and CD99. Clinical follow-up of eight patients showed an aggressive
biologic behavior with recurrence, metastasis, and death by tumor in five of
them 2 to 5 years after diagnosis. Based on these findings, the present tumors
are interpreted as an unusual spindle cell variant of thymic carcinoma. The
close association of these cases with areas showing the features of spindle cell
thymoma within the same tumor mass suggests that some of these lesions may arise
as a result of malignant transformation in a preexisting spindle cell thymoma.
|
