Other sex chromosome abnormalities, male phenotype, not elsewhere classified (Q98) ICD-10-CM
The Q98 code range covers other sex chromosome abnormalities, male phenotype, not elsewhere classified with 10 ICD-10-CM diagnosis codes. 9 of them are billable and valid for claim submission in fiscal year 2026, and the category headers group them but cannot themselves be billed.
Codes in the Q98 Range 10 codes · 9 billable
- Q98 Other sex chromosome abnormalities, male phenotype, not elsewhere classifiedNon-billable
- Q98.0 Klinefelter syndrome karyotype 47, XXY
- Q98.1 Klinefelter syndrome, male with more than two X chromosomes
- Q98.3 Other male with 46, XX karyotype
- Q98.4 Klinefelter syndrome, unspecified
- Q98.5 Karyotype 47, XYY
- Q98.6 Male with structurally abnormal sex chromosome
- Q98.7 Male with sex chromosome mosaicism
- Q98.8 Other specified sex chromosome abnormalities, male phenotype
- Q98.9 Sex chromosome abnormality, male phenotype, unspecified
Clinical Terms in This Code Range
Definitions from the National Library of Medicine for conditions coded in the Q98 range.
Gigantism
The condition of accelerated and excessive GROWTH in children or adolescents who are exposed to excess HUMAN GROWTH HORMONE before the closure of EPIPHYSES. It is usually caused by somatotroph hyperplasia or a GROWTH HORMONE-SECRETING PITUITARY ADENOMA. These patients are of abnormally tall stature, more than 3 standard deviations above normal mean height for age.
Klinefelter Syndrome
A form of male HYPOGONADISM, characterized by the presence of an extra X CHROMOSOME, small TESTES, seminiferous tubule dysgenesis, elevated levels of GONADOTROPINS, low serum TESTOSTERONE, underdeveloped secondary sex characteristics, and male infertility (INFERTILITY, MALE). Patients tend to have long legs and a slim, tall stature. GYNECOMASTIA is present in many of the patients. The classic form has the karyotype 47,XXY. Several karyotype variants include 48,XXYY; 48,XXXY; 49,XXXXY, and mosaic patterns ( 46,XY/47,XXY; 47,XXY/48,XXXY, etc.).
Sotos Syndrome
Congenital or postnatal overgrowth syndrome most often in height and occipitofrontal circumference with variable delayed motor and cognitive development. Other associated features include advanced bone age, seizures, NEONATAL JAUNDICE; HYPOTONIA; and SCOLIOSIS. It is also associated with increased risk of developing neoplasms in adulthood. Mutations in the NSD1 protein and its HAPLOINSUFFICIENCY are associated with the syndrome.
About the Q98 Code Range
The ICD-10 code Q98 covers other sex chromosome abnormalities affecting individuals with a male phenotype that are not classified elsewhere. These codes identify specific chromosomal conditions such as various types of Klinefelter syndrome and related disorders.
This section includes codes like Q98.0 for the classic 47,XXY Klinefelter syndrome and Q98.1 for Klinefelter variants with more than two X chromosomes (e.g., XXYY or XXXY). It also captures males with unusual karyotypes, such as 46,XX males under Q98.3, important for cases labeled as sex phenotype-karyotype dissociation syndrome or ovotesticular disorder of sex development. The code Q98.5 identifies 47,XYY syndrome, sometimes called Double Y syndrome. Other codes like Q98.7 and Q98.8 describe sex chromosome mosaicism and other specified abnormalities. These codes help medical coders accurately report conditions linked to sex chromosome differences in males, supporting proper diagnosis and treatment planning.
Questions About This Page
How many billable codes are in the Q98 range?
Of the 10 codes in this range, 9 are billable and valid for claim submission from October 1, 2025 through September 30, 2026. Category header codes group them but cannot be reported on claims.
What does the Q98 range classify?
The range classifies other sex chromosome abnormalities, male phenotype, not elsewhere classified. Each code links to its own reference page with billing status, MS-DRG grouping, coding notes, and clinical information.
Related References
Source: CMS FY 2026 ICD-10-CM Tabular List and order file, effective October 1, 2025 through September 30, 2026.
