Hypercalcemia due to malignant tumors including malignant lymphomas is relatively common.
Among cancer patients with hypercalcemia, humoral hypercalcemia of malignancy is the most
common and accounts for about 80% of all cases with hypercalcemia. 1,25-dihydroxyvitamin
D
3
(1,25(OH)
2
D
3
)-mediated
hypercalcemia is relatively rare. Although malignant lymphoma has been also reported to
cause 1,25(OH)
2
D
3
-mediated hypercalcemia, it
is not known whether there is any association between
1,25(OH)
2
D
3
-mediated hypercalcemia and any
specific histological type of malignant lymphoma. We herein report a case of an anaplastic
large cell lymphoma (ALCL), anaplastic lymphoma kinase (ALK) -negative with
1,25(OH)
2
D
3
-mediated hypercalcemia, which
has never been previously reported. An 80-year-old Japanese man was admitted to our
department due to acute exacerbation of hypercalcemia. He was diagnosed with ALCL,
ALK-negative. Serum 1,25(OH)
2
D
3
level was high
and seemed to be associated with the lymphoma because the serum calcium and
1,25(OH)
2
D
3
levels improved in response to
chemotherapy. Histological findings showed that many CD68 positive macrophages were
observed in the microenvironment of tumor cells. Lymphoma cells or tumor
microenvironmental cells may produce
1,25(OH)
2
D
3
because several previous reports
showed the source of 1,25(OH)
2
D
3
can be either
lymphoma or tumor microenvironmental cells. Moreover, because
1,25(OH)
2
D
3
-mediated hypercalcemia has been
reported regardless of the specific histological type of lymphoma, tumor
microenvironmental cells may be involved in this condition. However, we could not identify
the source of 1,25(OH)
2
D
3
in this case. The
association between 1,25(OH)
2
D
3
production and
prognosis in malignant lymphomas is yet unknown; further studies are needed to elucidate
the clinical characteristics of malignant lymphoma with
1,25(OH)
2
D
3
-mediated hypercalcemia.