Progressive transformation of germinal centres, abbreviated PTGCs and also progressive transformation of germinal centers, is a reactive lymph node

Lymph node

A lymph node is a small ball or an oval-shaped organ of the immune system, distributed widely throughout the body including the armpit and stomach/gut and linked by lymphatic vessels. Lymph nodes are garrisons of B, T, and other immune cells. Lymph nodes are found all through the body, and act as...

 process of undetermined etiology.

Symptoms

PTGC is usually characterized by localized lymphadenopathy

Lymphadenopathy

Lymphadenopathy is a term meaning "disease of the lymph nodes." It is, however, almost synonymously used with "swollen/enlarged lymph nodes". It could be due to infection, auto-immune disease, or malignancy....

 and is otherwise typically asymptomatic.

Diagnosis

PTGC is diagnosed by surgical excision of the affected lymph node(s), and examination by a pathologist. The differential diagnosis

Differential diagnosis

A differential diagnosis is a systematic diagnostic method used to identify the presence of an entity where multiple alternatives are possible , and may also refer to any of the included candidate alternatives A differential diagnosis (sometimes abbreviated DDx, ddx, DD, D/Dx, or ΔΔ) is a...

 includes non-neoplastic causes of lymphadenopathy (e.g. cat-scratch fever, Kikuchi disease

Kikuchi disease

Kikuchi's disease, also known as histiocytic necrotizing lymphadenitis and Kikuchi-Fujimoto disease, is a rare, non-cancerous enlargement of the lymph nodes....

) and malignancy, i.e. cancer

Cancer

Cancer , known medically as a malignant neoplasm, is a large group of different diseases, all involving unregulated cell growth. In cancer, cells divide and grow uncontrollably, forming malignant tumors, and invade nearby parts of the body. The cancer may also spread to more distant parts of the...

.

Microscopic appearance

PTGCs is characterized by:

• follicular hyperplasia (many follicles),
• focally large germinal centres, with poorly demarcated germinal centre (GC)/mantle zone interfaces (as GCs infiltrated by mantle zone lymphocyte
  Lymphocyte
  A lymphocyte is a type of white blood cell in the vertebrate immune system.Under the microscope, lymphocytes can be divided into large lymphocytes and small lymphocytes. Large granular lymphocytes include natural killer cells...
  
  s), and
• an expanded mantle zone
  Mantle zone
  The mantle zone of a lymphatic nodule is an outer ring of small lymphocytes surrounding a germinal center.It is also known as the "corona".It contains transient lymphocytes....
  
  .

Treatment

PTGC is treated by excisional biopsy and follow-up. It may occasionally recur and in a small proportion of patients has been reported to subsequently develop Hodgkin lymphoma (usually nodular lymphocyte predominant Hodgkin lymphoma).