AITL is more common in middle-aged and elderly men, the etiology is unknown, may be related to viral infection, allergic reactions, often have fever, rash, systemic lymph node enlargement, hepatosplenomegaly and other systemic symptoms, most of the patients are accompanied by abnormal immune function. The clinical manifestations of AITL are complex and changeable, often systematic, with large individual differences. Many patients mainly manifest fever, anemia, pruritus and systemic rash, even in dermatology for many years, until lymph nodes are enlarged. AITL is easy to be missed and misdiagnosed. 80% of the patients are in clinical stage Ⅲ ~ Ⅳ when the diagnosis is clear. The clinical characteristics of AITL can be summarized as systemic multi-system involvement caused by abnormal immune function, mainly as follows: (1) B symptoms: non-specific symptoms, such as fever, itching, rash, polyarthritis, anemia, body cavity effusion and so on. (2) Systemic lymphoid tissue involvement: systemic lymph node enlargement, hepatosplenomegaly, bone marrow involvement and so on. (3) Abnormal laboratory examination: lymphopenia, thrombocytopenia and accelerated erythrocyte sedimentation rate, eosinophil increase, β 2-microglobulin and lactate dehydrogenase increase. (4) Complicated with other tumors or syndromes. It has been reported that AITL was accompanied by Churg's syndrome, primary gastric cancer and chylous ascites. (5) The clinical course of AITL varies greatly: there are reports of spontaneous remission. Some of the pathogenesis is slow and some of the clinical processes are invasive, but most studies show that the prognosis of the disease is very poor.
The lymph nodes involved in AITL had the following morphological characteristics [3, 4]: 1) the structure of lymph nodes was destroyed in varying degrees, some of them had residual marginal sinus or follicles, branched blood vessels proliferated significantly, and some patients had hyaline degeneration of vascular wall with deposition of glycogen staining positive materials. 2) Lymphoma cells vary in size, with rich cytoplasm, light staining, pleomorphic or round nuclei and fine chromatin. 3) Plasma cells, eosinophils, reactive small lymphocytes and histiocytes are scattered. Tumor cells express specific markers: tumor cells express T cell differentiation antigen CD3, Most tumor cells express CD4, not as much as CD7 and CD8, express CD10, CXCL13, Bc-l6 and PD-1 at the same time. The histomorphology and immunohistochemistry of lymph nodes in this patient were consistent with the typical AITL characteristics. Positive CD10 is an important phenotype in the diagnosis of AITL and extranodal lesions. The expression of CXCL13 is helpful to describe the morphological spectrum of AITL, which further supports that AITL comes from helper T cells. The results of lymph node imprint in this case are consistent with the pathological results, which is of reference value for the rapid diagnosis and differential diagnosis of malignant lymphoma.
The main points of differentiation from pulmonary sarcoidosis and AITL are: (1) Both of them may have intrathoracic lymph node involvement and superficial lymph node enlargement, but lymphoma clinically has fever, emaciation, anemia, hepatosplenomegaly, and obvious symptoms of mediastinal compression, such as irritant cough and wheezing caused by tracheal pressure, superior vena cava syndrome, hoarseness caused by mediastinal nerve compression. The clinical symptoms of sarcoidosis are few and mild. (2) The lymph nodes of patients with lymphoma were gradually enlarged and fused into masses, mainly paratracheal lymph nodes, often involved retrosternal lymph nodes at the same time. Chest X-ray films often show unilateral or bilateral asymmetrical hilar lymph nodes enlarged, hilar lymph nodes tend to fuse with the right cardiac margin [5]. Lateral films show that enlarged mediastinal lymph nodes fill the anterior superior mediastinum area, which is the characteristic of lymphoma. The vast majority of bilateral hilar lymph nodes in sarcoidosis are symmetrically enlarged, or with enlarged mediastinal lymph nodes. The enlarged lymph nodes are limited to the hilum and paratrachea, often separated from the right cardiac margin, and each enlarged lymph node can be identified. After sarcoidosis appeared in the lung, the intrathoracic lymph node enlargement stopped developing, shrinking or dissipating, while malignant lymphoma showed pathological changes in the lung, the enlarged lymph nodes continued to develop and enlarge [6]. (3) Tissue biopsy and Kveim skin test are the main differential methods, and the positive rates of superficial lymph node biopsy and mediastinoscopic lymph node biopsy are higher.
The early clinical manifestation of this patient was not significantly specific to pulmonary sarcoidosis. Although the chest CT showed symmetrical hilar lymph node enlargement and pulmonary interstitial manifestations, it was difficult to differentiate from II stage pulmonary sarcoidosis. However, the hilar lymph nodes in chest CT tended to fuse, and the condition worsened after glucocorticoid treatment. It is suggested that the diagnosis should be confirmed by pathological biopsy of lymph nodes.
HE staining and immunohistochemical staining of lymph nodes have diagnostic value for this patient, and many pathological indexes are consistent with AITL.
In case of superficial lymph node enlargement and fever, lymph node biopsy should be performed early to avoid misdiagnosis or delayed diagnosis of malignant diseases.
AITL is a unique subtype of T-cell lymphoma, and there is no standard treatment at present. At present, CHOP chemotherapy is still used as a first-line treatment, supplemented by local radiotherapy, autologous stem cell transplantation and so on. However, the therapeutic effect of CHOP regimen is poor, and the recurrence rate is high and the maintenance time is short [7]. Because AITL is often accompanied by abnormal immune function, which leads to higher infection complications, which may be the reason for the poor effect of chemotherapy. The patient's condition improved after 3 cycles of chemotherapy with modified CHOP regimen.