Shimoyama smoldering or chronic-favourable subtype of ATLL. Smoldering: ≥5% circulating a...

Deterministic view of the source YAML entity. Clinical authority remains with the cited source IDs and reviewer sign-off state.

ID	`RF-ATLL-SHIMOYAMA-INDOLENT`
Type	Red flag
Status	reviewed 2026-05-08
Diseases	`DIS-ATLL`
Sources	`SRC-ESMO-PTCL-2024` `SRC-NCCN-BCELL-2025`

Red Flag Origin

Definition	Shimoyama smoldering or chronic-favourable subtype of ATLL. Smoldering: ≥5% circulating abnormal lymphocytes, no organ involvement (skin/lung lesion permitted), LDH normal, BUN normal, albumin normal, no hypercalcemia, no lymphadenopathy or organomegaly. Chronic-favourable: similar to smoldering but lymphadenopathy/organomegaly permitted, LDH ≤2× ULN, BUN ≤ULN, albumin ≥ULN, Ca normal, no CNS/bone/GI/effusion. AZT+IFN-α (anti-HTLV-1 mechanism) yields 5-yr OS ~46% vs ~20% for chemotherapy in these subtypes (Bazarbachi 2010 meta-analysis, JNCI). Aggressive subtypes (acute/lymphoma/chronic-unfavourable) do NOT respond to AZT+IFN — route those to CHOEP+mogamulizumab via RF-ATLL-HIGH-RISK-BIOLOGY.
Clinical direction	de-escalate
Category	other
Shifts algorithm	ALGO-ATLL-1L

Trigger Logic

{
  "any_of": [
    {
      "finding": "shimoyama_subtype",
      "value": "smoldering"
    },
    {
      "finding": "shimoyama_subtype",
      "value": "chronic_favourable"
    },
    {
      "finding": "shimoyama_subtype",
      "value": "chronic-favourable"
    },
    {
      "finding": "atll_subtype",
      "value": "smoldering"
    },
    {
      "finding": "atll_subtype",
      "value": "chronic_favourable"
    },
    {
      "finding": "atll_subtype",
      "value": "chronic-favourable"
    },
    {
      "finding": "shimoyama_indolent",
      "value": true
    }
  ],
  "type": "clinical_classification"
}

Notes

Shimoyama 1991 (JNCI 83:1034) is the gold-standard ATLL prognostic classifier. Four subtypes: smoldering / chronic-favourable / chronic- unfavourable / acute / lymphoma. This RF captures only the indolent end; chronic-unfavourable routes to aggressive track via lack of this RF (falls through to CHOEP default). Draft pending two-reviewer clinical co-lead signoff (CHARTER §6.1). Exclusion safety: step 1 screens for RF-ATLL-ORGAN-DYSFUNCTION + RF-ATLL-HIGH-RISK-BIOLOGY first — this RF only fires at step 2 after those are negative, so hypercalcemia/aggressive-subtype patients are already routed to CHOEP before this RF is evaluated.

Used By

Algorithms

ALGO-ATLL-1L - ALGO-ATLL-1L