PET-CT Report - Clinical Correlation & Action Plan

What the PET-CT Shows

• Brain, lungs, liver, spleen, pancreas, bone marrow: all clear
• No lymphadenopathy, no abdominal/pelvic disease
• Raj remains in the low-risk stratum (no risk-organ involvement)

Clinical Interpretation

Action Plan (5 Steps)

1. Confirm active LCH vs. infection, reactive change, or secondary malignancy
2. Test for BRAF V600E mutation (~55% of LCH cases carry this)
3. If BRAF-negative: run MAP2K1/MAPK pathway panel

• BRAF V600E (tissue + liquid biopsy/cfDNA)
• Full MAPK panel
• CBC, LFTs, LDH, ferritin
• Urine osmolality + serum sodium baseline (for DI monitoring)

• If BRAF V600E positive: Vemurafenib or Dabrafenib (± Trametinib). Strong response rates in relapsed/refractory LCH, though relapse on discontinuation is near-universal - likely requiring long-term therapy. Tovorafenib (panRAF inhibitor) is an emerging option.
• If BRAF negative (MAPK mutated): Cobimetinib (MEK inhibitor, FDA-approved for histiocytic neoplasms) or Trametinib/Binimetinib.
• If BRAF/MAPK negative or targeted therapy unavailable: Cladribine (~80% ORR, first choice), Cladribine + Cytarabine (CLARAC), or Clofarabine (third-line).

• Monitor serum sodium daily during chemo; use only isotonic IV fluids
• Avoid vincristine if possible (SIADH risk); if used, monitor sodium aggressively
• Continue DDAVP at current dose - do not adjust empirically
• Check morning urine + serum osmolality at each cycle start

Bottom Line

Biopsy Report Interpretation - Oncomine Focus Assay (52-Gene Panel)

What the Result Says

"No clinically significant gene variants identified in the tested panel."

• DNA sequence variants: including BRAF, MAP2K1, MAP2K2, KRAS, NRAS, RAF1, and all other major MAPK pathway genes
• Copy number variations: including BRAF, EGFR, MET, and 18 others
• Gene fusions: including BRAF, RAF1, NTRK1-3, FGFR1-3, and ALK

• BRAF V600E (found in ~55% of LCH) - not present
• MAP2K1/MAP2K2 mutations - not present
• Other MAPK pathway alterations (KRAS, NRAS, RAF1) - not present
• NTRK, FGFR, ALK fusions - not present

Important Caveat

What This Means for Treatment

Treatment Plan - BRAF/MAPK-Negative Relapsed Multifocal Bone LCH

Option 1 - Salvage Chemotherapy (First Choice)

• Standard first-choice salvage for relapsed/refractory LCH
• Overall response rate ~81% in adults (Harrison's, p. 925; Goldman-Cecil, p. 1784)
• Dosing: 5 mg/m² IV daily x 5 days, every 4 weeks x 4-6 cycles
• Well tolerated; myelosuppression is the main toxicity

• Preferred over cladribine alone for more aggressive relapse or prior cladribine failure
• Goldman-Cecil (2025): "Cladribine and high-dose cytarabine may be effective in relapsed/refractory settings."
• Applicable here given: multifocal disease, post-first-line reactivation, high SUVmax (16.1)

• Alternative if cladribine not tolerated

• Reserved as third-line if above fail

Option 2 - MEK Inhibitor (Consider Despite "Negative" Panel)

1. Assay limitations - 30% tumor cellularity with possible subthreshold mutations not detected
2. Known biology - virtually all LCH is driven by MAPK pathway activation, even if the specific mutation is not detectable by a 52-gene panel. Rare or atypical MAPK alterations may lie outside panel coverage.
3. Trametinib has shown 71% response rate in histiocytic neoplasms including BRAF-negative cases with other MAPK pathway mutations (Harrison's, p. 925)
4. Cobimetinib is FDA-approved for histiocytic neoplasms without BRAF V600E

Option 3 - Local Therapy (Adjunct, Not Sole Treatment)

• Low-dose involved-field radiotherapy: 6-10 Gy to the right frontal lesion
• Indicated if soft tissue extension threatens neurovascular structures or causes pain
• Use as a bridge to systemic therapy, not as standalone treatment given multifocal disease

Recommended Immediate Steps

Summary

Is "No Mutation Found" Good or Bad?

For LCH specifically: Having the BRAF V600E mutation is actually better from a treatment standpoint.

Is There a Tablet Treatment for Raj?

1. The result may not be the final word

• VE1 immunohistochemistry (IHC) - a simpler stain on the same biopsy block
• Liquid biopsy (blood test) - looks for tumor DNA circulating in the blood

2. MEK inhibitor tablets - a possible option even now

3. Tovorafenib (newest option)

Bottom Line for Raj's Family

• Not having a mutation is not ideal in LCH because it closes the easy tablet-treatment door
• However, it does not mean no tablet treatment - MEK inhibitor tablets (cobimetinib, trametinib) are a real option and should be actively discussed with the oncologist
• Before accepting "no mutation," two more tests should be done - IHC staining and a blood liquid biopsy - because the original test had borderline tumor cellularity
• If those also come back negative, the starting treatment will be IV chemotherapy (cladribine), which is effective but requires hospital visits
• The disease is still low-risk in terms of organ involvement - no liver, spleen, or bone marrow disease - which means the prognosis remains favorable regardless of mutation status

What is BRAF?

Normal cell:
Growth signal → RAS → BRAF → MEK → ERK → Cell grows → STOPS

What is the BRAF V600E Mutation?

Mutated cell:
No signal needed → BRAF stuck ON permanently → MEK → ERK → Cell keeps growing FOREVER

Why Does This Matter for Treatment?

BRAF Mutation in LCH - Key Facts

So Why Was Raj's Test Negative?

1. Raj genuinely does not have the mutation (~45% of LCH patients are truly BRAF wild-type) - in which case targeted therapy is not available this way
2. The mutation is present but was missed - the biopsy had only 30% tumor cells, which is at the margin of reliable detection. Low tumor cell content means a real mutation can be below the assay's detection limit (5% threshold for SNVs)
3. A different MAPK mutation is driving his disease - MAP2K1 or others - which responds to MEK inhibitors instead

What Should Be Done Next (BRAF-specific)

Simple Summary

• BRAF is a normal gene; BRAF V600E is a mutation that locks a cell growth switch permanently ON
• In LCH, having this mutation is not bad luck in terms of treatment - it opens the door to oral targeted tablets
• Raj's current test said "no mutation" but the test may not be fully reliable due to low tumor cell content
• Two more simple tests (IHC on the biopsy block + blood liquid biopsy) should be done urgently before concluding no mutation exists
• If confirmed negative, MEK inhibitor tablets (cobimetinib, trametinib) are still a potential oral option via a different but related mechanism

Gene Therapy for LCH - The Full Picture

First - What "Gene Therapy" Means

1. Correcting/replacing a faulty gene (classic gene therapy - viral vectors, CRISPR)
2. Blocking a mutant gene's product (targeted therapy - this is where LCH treatment actually is today)

Why LCH is a Good Candidate for Gene-Targeted Treatment

• Only one pathway is broken
• That pathway has known, druggable proteins
• Blocking it shuts down the disease without harming most normal cells

What Actually Exists Right Now (2025-2026)

Approved / Available Targeted (Gene-Directed) Therapies

Active Clinical Trials (2025-2026)

1. Tovorafenib (DAY101) - Pan-RAF Inhibitor

• A newer class of RAF inhibitor - works differently from vemurafenib/dabrafenib
• Phase 2 trial ongoing at Texas Children's and other centers for relapsed/refractory LCH
• Works even in patients with uncommon RAF alterations
• Oral tablet, once weekly dosing

2. Mirdametinib - MEK Inhibitor

• Phase 2 trial recruiting (NCT06153173) - testing in newly diagnosed AND relapsed/refractory LCH
• Specifically relevant for BRAF-negative patients like Raj
• Oral tablet with potentially fewer side effects than older MEK inhibitors
• Trial info at clinicaltrials.gov

3. Cobimetinib - NACHO COBI Trial

• Phase 2 at Texas Children's Hospital
• Testing cobimetinib in refractory LCH including BRAF-negative patients
• Already FDA-approved for histiocytic disorders (off-label use is possible now)

4. LCH-IV Trial (Histiocyte Society)

• International trial comparing standard chemotherapy regimens in pediatric/young adult LCH (NCT02205762)
• Best evidence-building trial for front-line and relapsed disease

True Gene Therapy (CRISPR / Viral Vector) - Where Does It Stand?

What This Means Specifically for Raj

1. Cobimetinib is available now - FDA-approved for histiocytic neoplasms, usable off-label in India via compassionate use or import. This is the most immediate oral targeted option.
2. Mirdametinib trial - If Raj can access an enrolling center (primarily US/Europe currently), this Phase 2 trial is highly relevant.
3. Tovorafenib (DAY101) trial - Works pan-RAF, so could help even without classical BRAF V600E. Worth asking the treating oncologist about trial access.
4. Luvometinib - Newly approved in China in May 2025 - if accessible via import or compassionate use, this is a MEK inhibitor approved for exactly this situation.
5. True gene therapy (CRISPR/viral) - Not available and not imminent. This is a 10+ year horizon for LCH.

Simple Summary

• "Gene therapy" in the traditional sense (fixing the gene itself) does not exist for LCH yet
• But targeting the gene's broken output with oral tablets (BRAF/MEK inhibitors) is the most active and fastest-advancing area in LCH treatment
• For Raj specifically (BRAF-negative), cobimetinib and mirdametinib are the most relevant oral targeted options available today
• A new MEK inhibitor, luvometinib, was approved in China in May 2025 specifically for LCH - a significant recent development
• The best path is enrolling in a clinical trial if possible, as this gives access to emerging drugs and expert monitoring

Blood Report Interpretation - Raj, 25M | Collected: 10 Jun 2026

QUICK SUMMARY FIRST

1. INFLAMMATION - hs-CRP: 20.6 mg/L (Normal: <3)

• hs-CRP is a protein the body releases when there is active inflammation or tissue damage anywhere
• Normal is under 3. Raj's is 20.6 - nearly 7 times the upper limit
• Values above 10 specifically indicate non-cardiac, systemic inflammation - the lab itself flags this
• In Raj's context, this directly confirms active LCH disease activity - the new skull and rib lesions seen on PET-CT are causing systemic inflammatory response
• This is a useful marker to track treatment response - if CRP falls after starting salvage therapy, it confirms the treatment is working
• Action: This is not a new problem - it is consistent with his active relapse. Report it to the oncologist; it can serve as a baseline before treatment starts.

2. COMPLETE BLOOD COUNT (CBC)

Hemoglobin: 14.3 g/dL ✅ Normal

RBC Indices - Iron Deficiency Pattern:

• Despite having a normal hemoglobin now, the iron stores are being depleted - early/pre-anemia iron deficiency
• Transferrin saturation is 14.4% (borderline low end of normal - 13-45%)
• TIBC is high-normal (426 µg/dL), which is the body trying to absorb more iron
• Action: Start oral iron supplementation (ferrous sulfate or ferrous bisglycinate). Dietary iron increase (red meat, leafy greens, avoid tea with meals).

WBC: 7.81 × 10³/µL ✅ Normal

• Neutrophils 60.5%, Lymphocytes 34.4% - perfectly balanced
• No immature cells (blasts/bands) - bone marrow not stressed
• This confirms the bone marrow is not infiltrated by LCH - consistent with PET-CT findings showing no diffuse bone marrow uptake

Platelets: 351 × 10³/µL ✅ Normal

Hematocrit (PCV): 50.9% (Normal: 40-50%)

3. VITAMIN D: 15.9 ng/mL (Normal: ≥30) 🔴

• Normal requires ≥30 ng/mL; Raj is at 15.9 - firmly in the deficiency zone (<20)
• Vitamin D is essential for bone health, immune regulation, and calcium absorption
• In LCH, the disease itself creates lytic (destructive) bone lesions - Vitamin D deficiency on top of this makes bone healing much harder and worsens bone loss
• Low Vitamin D is also linked to impaired immune function and higher inflammatory states
• Action: Start Vitamin D3 supplementation urgently - typically 60,000 IU weekly for 8-12 weeks (loading dose), then 1000-2000 IU daily maintenance. Must be done under medical supervision.

4. TESTOSTERONE: 173 ng/dL (Normal: 280-800) 🔴

• Normal for a young man is 280-800 ng/dL; Raj is at 173 - well below the lower limit
• In LCH, this is a classic and expected finding - LCH frequently involves the pituitary gland and hypothalamus, disrupting the hormonal axis
• Raj already has Diabetes Insipidus (DI) - which also comes from pituitary/hypothalamic LCH involvement
• Low testosterone in his case is most likely hypogonadotropic hypogonadism - the pituitary is not sending LH/FSH signals to the testes due to LCH damage
• Consequences: fatigue, reduced muscle mass, low energy, low libido, long-term bone density loss
• Action: Must check LH, FSH, and prolactin levels to confirm the cause. Refer to an endocrinologist. Testosterone replacement therapy (TRT) may be needed. This is a known late complication of LCH and should be formally evaluated.

5. LIPID PROFILE 🔴 - Significantly Deranged

• Important caveat: The lab notes that 10-12 hours fasting is mandatory for lipid testing - it is not confirmed whether Raj was fasting. If not fasting, triglycerides and LDL could be falsely elevated. Repeat fasting lipid profile before acting on this.
• If confirmed fasting, this represents dyslipidemia - elevated LDL + borderline triglycerides + low HDL
• Low testosterone (above) contributes to unfavorable lipid patterns
• Systemic inflammation (high CRP) is also linked to lipid derangement
• Action: Confirm with a fasting repeat test. Dietary changes (reduce saturated fats, fried foods, processed food). If LDL remains >130 mg/dL on fasting test in a 25-year-old with active disease, statin therapy may be needed.

6. LIVER FUNCTION TESTS

• Mildly elevated GGT (70 vs <55): GGT rises with alcohol intake, fatty liver, bile duct issues, or can be a non-specific marker of systemic inflammation. In Raj's context, it is most likely inflammation-related given the very high CRP
• Elevated globulin: Globulins include antibodies and inflammatory proteins. Elevated in the setting of active infection, inflammatory disease, or active LCH - consistent with the overall picture
• Normal AST, ALT, albumin: The liver is functionally intact - no hepatic infiltration by LCH (very reassuring, as liver involvement would make this high-risk LCH)
• Action: Monitor GGT at next blood test after treatment starts. If it rises further, investigate further.

7. KIDNEY FUNCTION ✅ All Normal

• Kidneys are functioning well - important before starting chemotherapy
• Sodium: 144.27 mmol/L - within normal (136-145). This is critical to monitor given Raj's DI. Currently stable, DDAVP is working.
• Uric acid is 7.4 (upper limit 7.3) - marginally above normal. Can rise with tissue breakdown from active disease or as a pre-gout indicator. Monitor.

8. THYROID: All Normal ✅

9. HbA1c: 5.5% ✅ Normal

10. VITAMIN B12: 486 pg/mL ✅ Normal (197-771)

Overall Interpretation in Context of LCH

1. Active systemic inflammation (CRP 20.6) - directly reflecting his ongoing LCH reactivation
2. Pituitary axis damage from LCH - seen in both the low testosterone AND the pre-existing DI (sodium is currently controlled with DDAVP)
3. Early iron deficiency - likely dietary, not disease-related (bone marrow is intact)
4. Vitamin D deficiency - needs urgent correction, especially with active bone disease
5. Dyslipidemia - needs fasting confirmation, likely partly driven by low testosterone and inflammation
6. Preserved organ function - liver, kidneys, thyroid, bone marrow all normal. This is good news and means he is safe to receive chemotherapy.

Action Points for the Doctor

Comparative Blood Report Analysis

MASTER COMPARISON TABLE

DETAILED INTERPRETATION BY SYSTEM

1. INFLAMMATION (hs-CRP): 26.94 → 20.6 mg/L 🟢 Improving but still very high

• In April, the CRP was 26.94 - this was during a period when the disease was building up silently after chemotherapy ended. The PET-CT in May then confirmed active new lesions.
• In June, it has come down to 20.6 - despite the disease being confirmed as active relapse. This is somewhat paradoxical.
• Possible explanation: Raj may have had a concurrent mild infection or inflammatory episode in April, which inflated the CRP even further. The LCH-driven inflammation alone accounts for the current 20.6.
• Bottom line: CRP is still far too high and confirms ongoing active disease. The slight fall is encouraging but not sufficient. This number should be used as a treatment response marker - once salvage therapy begins, falling CRP will confirm it is working.

2. WHITE BLOOD CELLS & IMMUNE PICTURE: Significant improvement 🟢

• In April, the lymphocyte count was elevated above the reference range at 3.42. This is consistent with a reactive lymphocytosis - the immune system was in a heightened state, likely responding to active LCH infiltration and/or post-chemo immune reconstitution.
• By June, lymphocytes have normalized to 2.69. The immune system is calmer, and bone marrow output appears more regulated.
• No blasts, no immature granulocytes in either report - the bone marrow is not producing abnormal cells. This is crucial - it rules out transformation to a more aggressive disease.
• This improvement is a positive sign - the immune system reconstituted well after chemotherapy.

3. TESTOSTERONE: 126 → 173 ng/dL 🟢 Improving but critically low

• The improvement suggests the hypothalamic-pituitary axis has some residual function and is partially recovering
• However, 173 is still well below the normal minimum of 280 for a 25-year-old male. He is symptomatic in the hypogonadal range.
• The improvement may be from: reduced overall inflammatory burden (inflammation suppresses testosterone production), or natural fluctuation
• It does NOT remove the need for formal endocrine workup. LH, FSH, prolactin must still be checked.
• The trajectory is positive but the absolute value is still deeply inadequate for a 25-year-old. If the pituitary damage from LCH is permanent, testosterone will not recover to normal on its own.
• Action: Endocrine consultation remains urgent. Even if slightly rising, he is likely to need testosterone replacement therapy.

4. VITAMIN D: 14.5 → 15.9 ng/mL 🟡 Marginal improvement, still deficient

• This tiny rise suggests either no supplementation was started, or a very low dose was taken inconsistently
• In a 25-year-old with active lytic bone lesions (LCH skull and rib lesions confirmed on PET-CT), Vitamin D deficiency is not a passive finding - it actively impairs bone repair and healing
• Action: This needs aggressive correction immediately. Oral Vitamin D3 60,000 IU weekly for 8 weeks (loading), then daily maintenance. Also check PTH and calcium panel to assess bone metabolism fully.

5. LIPIDS: Across-the-board improvement 🟢 but still deranged

• A consistent improvement across all lipid parameters over 7 weeks is noteworthy
• This could reflect dietary changes, reduced inflammation, or the mild rise in testosterone (testosterone improves lipid profiles)
• However, all parameters remain significantly above target. LDL of 158 is still in the "high" range.
• Both tests have fasting status unknown. A confirmed fasting repeat lipid test is needed before considering medication.
• If confirmed fasting and LDL still >130 in a young man with active inflammatory disease, statin therapy would be appropriate.

6. LIVER: GGT improving, SGPT rising 🟡 Mixed

• GGT is improving (74.9 → 70.23) - still mildly elevated but trending in the right direction
• SGPT has risen from 28.4 to 37.08 - still within normal limits (<45), but a 30% increase in 7 weeks warrants attention
• Albumin improvement (3.91 → 4.25) is a positive sign - indicates better nutritional status and liver synthetic function
• No hepatic infiltration by LCH - liver is structurally and functionally safe
• Watch the SGPT trend - if it continues rising before chemotherapy starts, investigate further

7. SODIUM: 145.3 → 144.27 mmol/L 🟢 Normalized

• DDAVP management is working better now
• This is good news before starting salvage chemotherapy - sodium control will be critical during treatment cycles
• Continue monitoring closely throughout therapy

8. URIC ACID: 8.26 → 7.4 mg/dL 🟢 Improving

• Was clearly elevated in April at 8.26 (normal max 7.3). Now marginally above at 7.4.
• High uric acid in LCH can reflect increased cell turnover from active disease. The fall is consistent with the modest decrease in disease activity
• Still borderline - if starting chemotherapy, watch for tumor lysis syndrome (further uric acid rise as treatment kills tumor cells). Allopurinol may be needed prophylactically before first chemo cycle.

9. HbA1c: 5.7% → 5.5% 🟢 Improved

• In April, HbA1c was exactly at the prediabetic threshold (5.7%). In June, it has dropped to 5.5% - back in the clearly normal range.
• This improvement in blood sugar over 7 weeks, without any intervention, likely reflects improved dietary habits or reduced stress hormone levels
• Good news before chemotherapy - no diabetic complications to worry about

THE BIG PICTURE: What Do These Changes Mean Together?

What the April 2026 report showed:

What the June 2026 report shows:

• Inflammation down (CRP 26.94 → 20.6)
• White cells normalized
• Testosterone slowly recovering
• Lipids improving
• Sodium better controlled
• Uric acid coming down
• Albumin up

Why might things improve while disease is active?

1. The April blood was drawn before the relapse was diagnosed - he may have had additional stress, infection, or was at peak inflammatory response. June represents the "settled" active disease state.
2. Psychological and lifestyle factors - knowing his diagnosis, he may be eating better, resting more, taking basic supplements.
3. The disease, while confirmed, has not worsened further - no new organ involvement since April. The body is in a sort of equilibrium with the disease.

What still needs urgent attention:

One-Line Summary