DxCodebookFY2027 · Oct 1, 2026 – Sep 30, 2027

B59 diagnosis code · Billable category · FY2027

B59 Pneumocystosis

  • Billable
  • MCC
  • HCC 6
  • POA reported

B59 ICD-10 code: a billable diagnosis code in FY2027; the category has no subdivisions.

Where it sits

  1. Chapter 1 Certain infectious and parasitic diseases (A00-B99)
  2. B50-B64 Protozoal diseases (B50-B64)
  3. B59 Pneumocystosis
CC / MCC
MCC
MS-DRG
177-179, 791, 793, 974-976
HCC V28
6
POA
Reported
Code Editor
–
Index entries
10

Instructions

At B59

Inclusion terms

  • Pneumonia due to Pneumocystis carinii
  • Pneumonia due to Pneumocystis jirovecii

Notes that also apply

Block B50-B64 instructions (Excludes1 2): printed on the block page.

Chapter 1 instructions (Includes 1, Excludes2 5, Use additional code 1): printed on the chapter 1 page.

Index entries

  • Pneumocystis carinii pneumonia → B59
  • Pneumocystis jirovecii (pneumonia) → B59
  • Pneumocystosis (with pneumonia) → B59
  • Infection, infected, infective (opportunistic)Pneumocystis carinii (pneumonia) → B59
  • Infection, infected, infective (opportunistic)Pneumocystis jirovecii (pneumonia) → B59
  • Pneumonia (acute) (double) (migratory) (purulent) (septic) (unresolved)plasma cell (of infants) → B59
  • Pneumonia (acute) (double) (migratory) (purulent) (septic) (unresolved)Pneumocystis (carinii) (jirovecii) → B59
  • Disease, diseasedprotozoalpneumocystosis → B59
  • Pneumonia (acute) (double) (migratory) (purulent) (septic) (unresolved)in (due to)pneumocystosis (Pneumocystis carinii) (Pneumocystis jirovecii) → B59
  • Pneumonia (acute) (double) (migratory) (purulent) (septic) (unresolved)interstitialplasma cell → B59

NCHS Alphabetic Index. Index first, then the Tabular List.

Medicare grouping and edits

CMS files for B59
CC / MCCMCC
PDX exclusion list0240 (105 codes)
Appendix BMDC 04 Diseases and Disorders of the Respiratory System, MS-DRG 177-179 (Respiratory Infections and Inflammations with MCC…); MDC 15 Newborns and Other Neonates with Conditions Originating in Perinatal Period, MS-DRG 791 (Prematurity with Major Problems…); MDC 15 Newborns and Other Neonates with Conditions Originating in Perinatal Period, MS-DRG 793 (Full Term Neonate with Major Problems…); MDC 25 Human Immunodeficiency Virus Infections, MS-DRG 974-976 (HIV with Major Related Condition with MCC…)
Code Editor–
POAReported
HCC V28HCC 6 Opportunistic Infections

MCC as a secondary diagnosis, not when the principal diagnosis is on its PDX exclusion list.

CMS: MS-DRG v44 (Appendix B, C), MCE v44, POA list FY2027, 2027 Initial ICD-10-CM Mappings. What the rows mean.

Hierarchy