A patient of CD4-/CD8+ chronic T-cell leukemia associated with hypercalcemia

Hypercalcaemia associated with chronic lymphocytic leukaemia in a Giant Schnauzer

A 7-year-old male Giant Schnauzer was referred with a history of severe vomiting, lethargy, weight loss, polydipsia and polyuria. Detailed investigations revealed leucocytosis with a marked lymphocytosis, mild non-regenerative anaemia, thrombocytopenia, hypercalcaemia and azotaemia. Circulating lymphocytes were small and well-differentiated, and the same lymphoid population was present in bone marrow. Chronic lymphocyctic leukaemia with associated paraneoplastic hypercalcaemia was diagnosed. Immunohistochemical staining of a bone marrow biopsy revealed a neoplastic B-cell line expressing CD79. The dog responded to therapy with prednisolone and chlorambucil for a period of 8 months.

Parathyroid hormone-related protein in hypercalcemia associated with hematological malignancy

Hypercalcemia is an important complication in multiple myeloma as well as T-cell leukemia/lymphoma, and is moderately common in high and intermediate grade non-Hodgkin's lymphoma. The underlying mechanism has been unclear because the neoplastic cells are usually present in the bone marrow, where they are in a position to produce short range effects on bone resorption which are difficult to identify. This contrasts with the situation in hypercalcemia associated with non-metastatic carcinoma, where it has been clearly demonstrated that the most common cause is release from the tumor of a humoral mediator, Parathyroid Hormone-related Protein (PTHrP). Roles have been advocated in multiple myeloma for release of a number of other cytokines with osteolytic capacity on the basis of their enhancement of osteolytic activity in cultured fetal rat bone, although a causal relationship in patients has not been established. PTHrP has more recently been implicated in the genesis of hypercalcemia in patients with hematological malignancies by the demonstration in a proportion of cases of increased circulating levels of PTHrP, comparable to those in hypercalcemia due to cancer. Immunohistochemical studies indicate neoplastic hemopoietic cells can contain PTHrP, and thus have the capacity to act in a paracrine manner to enhance local bone resorption and contribute to the development of hypercalcemia.

A patient with primary hypoparathyroidism developing hypercalcemia associated with adult T-cell leukemia/lymphoma

A 38-year-old woman was admitted to our hospital with symptoms and signs of hypocalcemia in 1977 and a diagnosis of primary hypoparathyroidism was made with a positive Ellsworth Howard test. She was then lost to follow up until 1992 when she returned this time with symptoms and signs of hypercalcemia. An inguinal lymph node was biopsied showing non-Hodgkin's lymphoma, diffuse pleomorphic type and monoclonal integration of proviral human T-cell lymphotropic virus-1 DNA was detected in lymph node cells indicating ATLL. Serum parathyroid hormone-related peptide (PTHrP) was slightly elevated and the tumor cells were positively stained with anti-PTHrP serum. Combination chemotherapy with vincristine, adriamycin, cyclophosphamide and prednisolone was given to the patient with disappearance of the lymphadenopathy and subsequent normalization of PTHrP levels. Interestingly, the signs and symptoms of hypocalcemia reappeared after the treatment requiring replacement therapy with calcium and vitamin D.