Bone pain, pathologic fractures, weakness, anaemia, infection, hypercalcemia, spinal cord compression, and renal failure are all signs and symptoms of multiple myeloma (MM). The patient’s condition matched the signs and symptoms of myeloma.

Interleukin-1, which is released by leukocytes and acts on the thermoregulatory centre of the hypothalamus, causes fever. Because prostaglandins mediate this process, antipyretics such as NSAIDs, paracetamol, and aspirin reduce prostaglandin levels by inhibiting cyclooxygenase enzymes. Malignant disease secretes interleukins, which cause the B-symptoms seen in lymphoma, for example. Bacterial toxins can also cause interleukins to be produced.

Pyrexia of unknown origin (PUO) is defined as a fever of greater than 38.3 degrees Celsius that lasts for more than 2-3 weeks with no clear diagnosis despite extensive investigation.

Investigation necessitates a thorough understanding of the conditions that can cause febrile illness, which may be missed during an initial investigation, as well as a thorough history, examination, and investigation centred on that list.

Pyrexia of unknown origin has a wide differential diagnosis, which includes:
Infection
Bacterial
Pyogenic abscess
Tuberculosis
Infective endocarditis
Brucellosis
Lyme disease
Viral
HIV
Epstein Barr Virus
Cytomegalovirus
Parasite
Toxoplasmosis
Malignancy
Leukaemia
Lymphoma
Renal cell carcinoma
Hepatocellular carcinoma
Vasculitides
Still’s disease
Granulomatosis with polyangiitis (formerly Wegener’s)
Systemic lupus erythematosus
Giant cell arteritis
Rheumatoid arthritis
Polymyalgia rheumatica
Miscellaneous
Drug induced fevers
Familial Mediterranean fever
Thyrotoxicosis
Inflammatory bowel disease
Sarcoidosis
Factitious fever
Exaggerated normal circadian fluctuation

The patient might need to be admitted to the hospital for observation and further investigation. Because infection is still a possibility, blood cultures should be repeated on a regular basis, and inflammatory markers should be closely monitored. CT, PET, and MRI imaging have largely replaced diagnostic laparotomy as a diagnostic tool.

Myeloma laboratory findings include:
– The presence of a paraprotein in serum or urine (the paraprotein is IgG in 60 percent of cases, IgA in 20 percent, and light chain only in almost all the rest),
– Increased serum immunoglobulin-free light chain proteins generated by plasma cells but not coupled with heavy chains 
– Reduced IgG, IgA, and IgM levels in the blood (immune paresis)
– Anaemia, whether normochromic, normocytic, or macrocytic. 
– On a blood film, a Rouleaux formation has been marked.
– In advanced illness, neutropenia and thrombocytopenia are common.
– ESR is high.
– Plasma cells in the bone marrow are overabundant, typically in aberrant forms. – Hypercalcemia
– Creatinine levels are high.
– Serum albumin levels are low in advanced illness.
60 percent of patients have osteolytic lesions, osteoporosis, or pathological fractures.

A papule is a solid, well circumscribed, skin elevation measuring less than 0.5 cm in diameter.

A nodule is a solid, well circumscribed, raised area that lies in or under the skin and measures greater than 0.5 cm in diameter. They are usually painless.

A bulla is a visible collection of clear fluid measuring greater than 0.5 cm in diameter.

A furuncle, or boil, is a pyogenic infection of the hair follicle commonly caused by infection with Staphylococcus aureus.

A pustule is a small visible skin elevation containing an accumulation of pus.

Monocytes spend only a short time in the marrow and, after circulating for 20-40 hours, leave the blood to enter the tissues where they become macrophages. Macrophages form the reticuloendothelial system in the liver, spleen and lymph nodes. The lifespan of macrophages may be as long as several months or even years. In tissues the macrophages become self-replicating without replenishment from the blood. They assume specific functions in different tissues e.g. dendritic cells which are involved in antigen presentation to T-cells. Macrophages may be activated by cytokines such as IFN-gamma, contact with complement or direct contact with the target cell through leucocyte adhesion molecules.

Fat necrosis typically occurs following either direct trauma or from enzymatic lipolysis in acute pancreatitis, where release of triglyceride elicits a rapid inflammatory response and fat is phagocytosed by neutrophils and macrophages with subsequent fibrosis.

Anaemia of chronic disease is one of the most common causes of normocytic anaemia. The anaemia is usually mild (Hb > 90 g/L) and non-progressive. Anaemia of chronic disease is usually associated with low serum iron, low transferrin saturation, and a low total iron binding capacity (TIBC) with normal or raised ferritin which differentiates it from iron deficiency anaemia.

Blood group O has no antigens, but both anti-A and anti-B antibodies and thus is the universal donor.

Multiple myeloma is a clonal abnormality affecting plasma cells in which there is an overproduction of functionless immunoglobulins. The most common patient complaint is bone pain, especially in the back and ribs. Anaemia and renal failure are common, along with hypercalcemia. Hypercalcemia may lead to an altered mental status, as in this case.

Chronic lymphocytic leukaemia occurs due to the overproduction of lymphocytes, usually B cells. CLL may present with an asymptomatic elevation of B cells. Patients are generally more than 50 years old and present with non-specific fatigue and weight loss symptoms.

There is no history of alcohol abuse in this case. Furthermore, patients with a history of alcohol abuse may have signs of liver failure, which are not present here.

Metastatic prostate cancer would most often cause lower backache as it metastasises first to the lumbar spine via the vertebral venous plexus.

A patient with Vitamin B12 deficiency would have anaemia, megaloblastic, hypersegmented neutrophils, and signs of peripheral neuropathy.

Hodgkin’s lymphoma is a malignant tumour of the lymphatic system that is characterised histologically by the presence of Reed-Sternberg cells (multinucleated giant cells). The peak incidence is in young adults aged 20-35, and there is a slight male predominance.

The following are recognised risk factors for Hodgkin’s lymphoma:
Male gender
Age 20-35
Positive family history
Epstein-Barr virus infection
Immunosuppression including HIV infection
Prolonged use of human growth hormone
Most patients present with an enlarged, but otherwise asymptomatic lymph node. The most commonly affected lymph nodes are in the supraclavicular and lower cervical areas. Other common clinical features include shortness of breath and chest discomfort secondary to mediastinal mass. Mediastinal masses are sometimes discovered as incidental findings on routine chest X-rays. Approximately 30% of patients with Hodgkin’s lymphoma develop splenomegaly.
‘B’ symptoms occur in approximately 25% of patients. The ‘B’ symptoms of Hodgkin’s lymphoma are:
Fever (>38ºC)
Night sweats
Weight loss (>10% over 6 months)
Pain after alcohol consumption is a pathognomonic sign of Hodgkin’s lymphoma, it is, however, not a ‘B’ symptom. It is rare though, only occurring in 2-3% of patients with Hodgkin’s lymphoma.

The Ann Arbour clinical staging is as follows:
Stage I: one involved lymph node group
Stage II two involved lymph node groups on one side of the diaphragm
Stage III: lymph node groups involved on both sides of the diaphragm
Stage IV: Involvement of extra-nodal tissues, such as the liver or bone marrow
Diagnosis is made by lymph node biopsy, which should be taken from a sufficiently large specimen or excisional biopsy, as opposed to a fine needle biopsy. The Reed-Sternberg cell is the most useful diagnostic feature. This is a giant cell with twin mirror-image nuclei and prominent ‘owl’s eye’ nucleoli.
The Reed-Sternberg cell of Hodgkin’s Lymphoma
Histological typing depends upon the other cells within the diseased tissue. Nodular sclerosing is the most common type of Hodgkin’s lymphoma. Lymphocyte-depleted and lymphocyte-predominant are rare subtypes.
The majority of cases can be successfully treated, and unlike many other malignancies even if the first-line treatment fails, a cure can often be achieved with second-line therapies. Stage 1 Hodgkin’s lymphoma is usually treated with radiotherapy alone, but more advanced stages require combination chemotherapy. In localised disease treated with irradiation, there is a 5-year survival rate of greater than 80%. In disseminated disease treated with chemotherapy, the 5-year survival falls to around 50%. Overall, a 5-year survival of >70% should be achieved.