Chronic neutrophilic leukemia (CNL) is a rare myeloproliferative neoplasm that features a persistent neutrophilia in peripheral blood, myeloid hyperplasia in bone marrow, hepatosplenomegaly, and the absence of the Philadelphia chromosome or a BCR/ABL fusion gene. Signs and symptoms
The most common clinical finding is hepatosplenomegaly. Pruritus, gout, and mucocutaneous bleeding are occasionally seen. Cause
The cause of CNL is currently unknown. An association between CNL and multiple myeloma has been suggested based on the observation of myeloma in 20% of CNL cases. However, a clonal genetic abnormality has not been detected in these myeloma-associated cases of CNL, raising the possibility that the neutrophilia is a reaction due to the neoplastic myeloma cells. The postulated cell of origin is a limited-potential, marrow-derived stem cell. Genetics
The majority (90%) of cases have not had detectable cytogenetic abnormalities. Most importantly, the Philadelphia chromosome and other BCR/ABL fusion genes are not detected. Diagnosis
Laboratory findings
Peripheral blood neutrophilia (> 25 x 109/L) with myeloid precursors (promyelocytes, myelocytes, metamyelocytes) comprising less than 5% of leukocytes. Sites of involvement
Peripheral blood, bone marrow, spleen, and liver are most common, but any organ or tissue can be infiltrated by neutrophils. Bone marrow biopsy
On both the bone marrow aspirate and the core biopsy, a hypercellular marrow with an increased myeloid:erythroid ratio of 20:1 or greater. Myelocytes and neutrophils are increased, and blasts and promyelocytes are not increased. Due to the myeloproliferative nature of the disease, an increase in megakaryocytes and erythroid precursors may be observed, but dyspoiesis in not seen in any cell lineage. Also, reticulin fibrosis is rare.
Unconventional perception of the world
Maladaptive daydreaming, excessive daydreaming interfering with daily life

Diagnosis
PDD-NOS is an old diagnostic category. It is not included as an option for an Autism Spectrum Disorder and is not part of the DSM-5, but is included in the ICD-10, as either "atypical autism" or "pervasive developmental disorder, unspecified".The diagnosis of a pervasive developmental disorder not otherwise specified is given to individuals with difficulties in the areas of social interaction, communication, and/or stereotypic behavior patterns or interests, but who do not meet the full DSM-4 criteria for autism or another PDD. This does not necessarily mean that PDD-NOS is a milder disability than the other PDDs. It only means that individuals who receive this diagnosis do not meet the diagnostic criteria of the other PDDs, but that there is still a pervasive developmental disorder that affects the individual in the areas of communication, socialization, and behavior.As for the other pervasive developmental disorders, the diagnosis of PDD-NOS requires the involvement of a team of specialists. The individual needs to undergo a full diagnostic evaluation, including a thorough medical, social, adaptive, motor skills and communication history. Other parts of an assessment can be behavioral rating scales, direct behavioral observations, psychological assessment, educational assessment, communication assessment, and occupational assessment.Description of PDD-NOS merely as a "subthreshold" category without a more specific case definition poses methodological problems for research regarding the relatively heterogeneous group of people who receive this diagnosis.