Differential Diagnosis
- Single most likely diagnosis
- Acute graft-versus-host disease (GVHD): This is the most likely diagnosis given the patient's history of hematopoietic stem cell transplant 1 month ago and the presentation of a scaling maculopapular rash, oral mucositis, and bloody diarrhea. Acute GVHD typically occurs within the first 100 days after transplant and can affect the skin, gastrointestinal tract, and liver.
- Other Likely diagnoses
- Adverse effect from chemotherapy: Although the patient's last chemotherapy was before the transplant, some chemotherapy agents can have delayed effects. However, the timing and combination of symptoms (rash, bloody diarrhea, and oral mucositis) are more suggestive of GVHD.
- Typhlitis: This condition, also known as neutropenic enterocolitis, can occur in immunocompromised patients, especially after chemotherapy or stem cell transplant. It presents with abdominal pain, fever, and diarrhea, which could be bloody. However, the presence of a rash and oral mucositis points more towards GVHD.
- Do Not Miss
- Infection (e.g., CMV colitis or other opportunistic infections): In an immunocompromised patient, especially post-stem cell transplant, infections can be life-threatening and must be considered, even if less likely based on the initial presentation.
- Hemorrhagic cystitis: This condition can cause bloody diarrhea or hematuria and is associated with certain chemotherapy agents or infections. It's less likely given the rash and oral mucositis but should be considered due to its potential severity.
- Rare diagnoses
- Tumor lysis syndrome: This condition is characterized by the rapid release of intracellular contents due to cancer cell lysis, leading to metabolic abnormalities. It is less likely in this scenario because the patient's symptoms (rash, bloody diarrhea, oral mucositis) do not align closely with tumor lysis syndrome, which typically presents with acute kidney injury, hyperkalemia, hyperphosphatemia, and hypocalcemia.
- Other rare infections or drug reactions: There could be other rare infections or drug reactions that present similarly, but they would be less common and are not as directly suggested by the patient's history and symptoms as acute GVHD.