A bone marrow transplant is a procedure that infuses healthy blood-forming stem cells into your body to replace your damaged or diseased bone marrow. A bone marrow transplant is also called a stem cell transplant. You might need a bone marrow transplant if your bone marrow stops working and does not produce enough healthy blood cells. Bone marrow transplants may use cells from your own body (autologous transplant) or from a donor (allogeneic transplant)
Medications;  If your bone marrow transplant is using stem cells from a donor (allogeneic transplant), your doctors may prescribe medications to help prevent graft-versus-host disease and reduce your immune system's reaction (immunosuppressive medications).
After your transplant, it takes time for your immune system to recover. During this time, you may be given medications to prevent infections.

Introduction
Exogenous lipoid pneumonia (ELP) is a rare form of pneumonia caused by inhalation or aspiration of a fatty substance. ELP has been reported with inhalation or ingestion of petroleum jelly, mineral oils, “nasal drops,” and even intravenous injection of olive oil.  It is an important consideration in the differential diagnosis of several pulmonary syndromes because progression appears to be halted, or at least slowed, by stopping exposure to the offending lipid substance.
Case report
Here we are reporting an unusual case of a 45years old male with no prior co-morbid present with cough and shortness of breath referred to our specialty for lung biopsy. His CT scan revealed bilateral lung infiltrates, his open lung biopsy revealed: subpleural fibrosis, scarring, dense inflammation with widespread entrapped cholesterol clefts with foreign body giant cells in blood vessels and interstitium.
On further questioning, the patient admitted to the daily use of baby oil for dryness of hairs and body, the diagnosis of ELP was made caused by chronic improper use of baby oil. His condition improves after the discontinuation of baby oil.
Conclusion
The diagnosis of exogenous lipoid pneumonia is often difficult as symptoms, signs, and radiographic findings are all rather non-specific. We would like to emphasize the role of precise case history and histopathological diagnosis in the better identification of ELP. Treatment of ELP by total avoidance of causative agents is fundamental to achieving disease regression.