Malignant Terms

There are a number of diagnoses that are malignant and reportable but do not sound that way.

  • Atypical carcinoid
  • Rhabdoid tumor, NOS
  • Intratubular germ cell neoplasia
  • Epithelioid trophoblastic tumor
  • Mixed pineal tumor, transitional pineal tumor
  • Atypical teratoid/rhabdoid tumor
  • Pagetoid reticulosis
  • Generalized Langerhans cell histiocytosis
  • Agnogenic myeloid metaplasia
  • Acute progressive histiocytosis X
  • Heavy chain disease
  • Immunoproliferative small intestinal disease
  • Hypereosinophilic syndrome
  • Therapy-related myelodysplastic syndrome

Atypical carcinoid & typical carcinoid

Have different histology codes, and both have behavior codes of /3.


Spindle epithelial tumor with thymus-like element.


Carcinoma showing thymus-like element.

Rhabdoid tumor

One of the complex mixed and stromal neoplasms.

Intratubular germ cell neoplasia

An in situ term that you may recognize from the TNM staging of testicular cancer.

Epithelioid trophoblastic tumor

A new code in the hydatidiform mole series.

Mixed and transitional pineal tumors & atypical teratoid/rhabdoid tumor

In the CNS.

Pagetoid reticulosis

A synonym for mycosis fungoides.

Generalized Langerhans cell histiocytosis

Predominantly a disease of childhood.

Agnogenic myeloid metaplasia

A term used in the U.S. as a synonym for myelosclerosis.

Acute progressive histiocytosis X

A specific type of Histiocytosis X. Histiocytosis X was a term proposed by Dr. Lichtenstein in 1952 to embrace three disorders characterized by accumulation of histiocytes in different tissues: eosinophilic granuloma, Hand-Schuller-Christian syndrome, and Letterer-Siwe disease.

Heavy chain disease and immunoproliferative small intestinal disease

Are tumors that were already in ICD-O-2.

Hypereosinophilic syndrome (9964/3)

A new term with a new code and is a chronic myeloproliferative disorder of the bone marrow (C42.1).

Therapy-related myelodysplastic syndrome (9987/3)

Also a new term with a new code and also arises in the bone marrow (C42.1).