Plasma cell myeloma marrow diagnosis including morphologic and phenotypic features

Combined Immunohistochemistry after Mass Spectrometry Imaging for Superior Spatial Information

OBJECTIVE

Tissue slides analyzed by MS imaging (MSI) are stained by H&E (Haematoxylin and Eosin) to identify regions of interest. As it can be difficult to identify specific cells of interest by H&E alone, data analysis may be impaired. Immunohistochemistry (IHC) can highlight cells of interest but single or combined IHC on tissue sections analyzed by MSI have not been performed.

METHODS

We performed MSI on bone marrow biopsies from patients with multiple myeloma and stained different antibodies (CD38, CD138, MUM1, kappa- and lambda). A combination of CK5/6/TTF1 and Napsin-A/p40 is stained after MSI on adenocarcinoma and squamous cell carcinoma of the lung. Staining intensities of p40 after MSI and on a serial section are quantified on a tissue microarray (n = 44) by digital analysis.

RESULTS

Digital evaluation reveals weaker staining intensities after MSI as compared to serial sections. Staining quality and quantity after MSI enables to identify cells of interest. On the tissue microarray, one out of 44 tissue specimens shows no staining of p40 after MSI, but weak nuclear staining on a serial section.

CONCLUSION

We demonstrated that single and double IHC staining is feasible on tissue sections previously analyzed by MSI, with decreased staining intensities.

Plasma cell morphology in multiple myeloma and related disorders

Normal and reactive plasma cells (PC) are easy to ascertain on human bone marrow films, due to their small mature-appearing nucleus and large cytoplasm, the latter usually deep blue after Giemsa staining. Cytoplasm is filled with long strands of rough endoplasmic reticulum and one large Golgi apparatus (paranuclear hof), demonstrating that PC are dedicated mainly to protein synthesis and excretion (immunoglobulin). Deregulation of the genome may induce clonal expansion of one PC that will lead to immunoglobulin overproduction and eventually to one among the so-called PC neoplasms. In multiple myeloma (MM), the number of PC is over 10% in most patients studied. Changes in the morphology of myeloma PC may be inconspicuous as compared to normal PC (30-50% patients). In other instances PC show one or several morphological changes. One is related to low amount of cytoplasm, defining lymphoplasmacytoid myeloma (10-15% patients). In other cases (40-50% patients), named immature myeloma cases, nuclear-cytoplasmic asynchrony is observed: presence of one nucleolus, finely dispersed chromatin and/or irregular nuclear contour contrast with a still large and blue (mature) cytoplasm. A peculiar morphological change, corresponding to the presence of very immature PC named plasmablasts, is observed in 10-15% cases. Several prognostic morphological classifications have been published, as mature myeloma is related to favorable outcome and immature myeloma, peculiarly plasmablastic myeloma, is related to dismal prognosis. However, such classifications are no longer included in current prognostic schemes. Changes related to the nucleus are very rare in monoclonal gammopathy of unknown significance (MGUS). In contrast, anomalies related to the cytoplasm of PC, including color (flaming cells), round inclusions (Mott cells, Russell bodies), Auer rod-like or crystalline inclusions, are reported in myeloma cases as well as in MGUS and at times in reactive disorders. They do not correspond to malignant changes of PC but are related to abnormal synthesis, trafficking, or excretion of the immunoglobulin that is stored in excess within the cytoplasm. Occurrence of crystalline inclusions within PC may be the first anomaly leading to the diagnosis of adult Fanconi syndrome. After a historical perspective, the authors report on the various morphological aspects of PC that may occur in multiple myeloma and related disorders, and discuss about their clinical and pathophysiological significance. Today, morphological identification and accurate determination of % PC within bone marrow remain ancillary criteria for the diagnosis of MM and help for the diagnosis of rare renal disorders.

Bone-marrow plasma cell burden correlates with IgM paraprotein concentration in Waldenström macroglobulinaemia

Aims

Correlations between the marrow histopathology and clinical findings in Waldenström macroglobulinaemia (WM) are not well defined, and the pathophysiology of the plasma cell involvement is poorly understood. The authors used a standardised immunohistological approach to the enumeration of B lymphocyte and plasma cell compartments in the bone-marrow trephine to investigate associations between bone-marrow morphology and clinical/laboratory indices.

Methods

In 80 newly diagnosed, untreated cases of WM, the authors determined the degree and pattern of B lymphocyte (CD20+) and plasma cell (CD138+) infiltration in the bone-marrow trephine, as defined by immunohistochemistry, and correlated the disease in the marrow with components of the international scoring system for WM (age, serum IgM paraprotein level, haemoglobin, platelet count and β2 microglobulin). Plasma cell clonality was assessed by κ and λ staining.

Results

Serum IgM paraprotein concentration was related to the plasma cell burden in the bone marrow (coefficient 0.231, p<0.005), but not the B lymphocytic infiltrate. Overall lymphoplasmacytic disease burden weakly correlated with severity of anaemia (coefficient 0.236, p=0.055). In 28/28 evaluated cases, plasma cells exhibited light chain restriction that was concordant with both that of the B lymphocytic infiltrate and paraprotein.

Conclusions

Bone-marrow features, in particular the degree of plasma cell infiltration, correlate with IgM paraprotein concentration at diagnosis in WM. The plasma cell compartment in this condition appears to be part of the neoplastic clone. In WM, specific evaluation of the plasma cell compartment in the bone marrow at baseline and following therapy may be valuable.

Histopathologic, Immunohistochemical, and Cytologic Analysis of Feline Myeloma-Related Disorders: Further Evidence for Primary Extramedullary Development in the Cat

Feline myeloma-related disorders (MRD) are rare neoplasms of plasma cells. The multistep transformation model of myeloma in humans is based on the premise that plasma cells undergo neoplastic transformation primarily within the intramedullary compartment and that over time they become poorly differentiated and metastasize to extramedullary locations. Historically, diagnostic criteria used for human multiple myeloma have been applied to the cat, with the assumption that feline MRD commonly arises in the intramedullary compartment. Our objectives were to describe the features of feline MRD confirmed by cytology, histopathology, histochemistry, and immunohistochemistry and to categorize these tumors. A priori hypotheses were 1) tumor category predicts survival and 2) cats with well-differentiated tumors commonly have extramedullary involvement in contrast to human myeloma patients. This multicenter, retrospective study identified 26 MRD cases. There was good agreement between histopathologic and cytologic tumor categorization. Histochemistry and immunohistochemistry were shown to be valuable adjunct tests in the diagnosis of MRD. Cats with well-differentiated tumors had increased median survival relative to those with poorly differentiated tumors (254 versus 14 days). We have reported that marked extramedullary involvement at initial clinical presentation is significantly more common in the cat than in human MRD patients. In this study, we demonstrate that cats with well-differentiated tumors more commonly have extramedullary involvement than human myeloma patients with well-differentiated tumors (90% versus 20%, P < 0.0002). These results contrast strongly with the human myeloma model of primary intramedullary neoplastic transformation and suggest that primary extramedullary neoplastic transformation may be more common in feline MRD.

Diagnosis and Classification of Malignant Lymphoma and Related Entities in the Bone Marrow Trephine Biopsy

The trephine bone marrow (BM) biopsy is an important diagnostic tool in patients with malignant lymphoma. BM examination can serve to establish or confirm a primary diagnosis of lymphoma or to determine the extent of disease dissemination for staging purposes. BM histology renders information which cannot be gained equally from aspirate material, such as spacial distribution and extent of infiltrates, BM cellularity and fibrosis. Furthermore, cytology including flow cytometric immunophenotyping can give false-negative results in BM involvement by lymphoma due to intralesional fibrosis. In addition to morphological examination, the availability of a broad panel of antibodies suitable for paraffin-embedded tissues, in conjunction with less damaging decalcification procedures, nowadays enables us to perform complete immunophenotyping on BM trephines and allows for classification of lymphoma infiltrates according to established algorithms. Molecular determination of clonality and interphase fluorescent in situ hybridization can be employed selectively to resolve difficult cases. This review describes important diagnostic features of malignant lymphoma in the BM, relevant differential diagnoses, and the proper use of ancillary techniques.

Multiple myeloma in 16 cats: a retrospective study

BACKGROUND

There is limited published information regarding feline multiple myeloma. Diagnostic criteria are derived from canine studies and to our knowledge, have not been critically reviewed for cats.

OBJECTIVE

To evaluate the clinical and laboratory findings in cats with multiple myeloma and appraise diagnostic criteria.

METHODS

Retrospective evaluation of medical records was performed. Inclusion required an antemortem diagnosis of multiple myeloma using 2 of 4 criteria: 1) >or=20% plasma cells in the bone marrow, or >or=10% if atypical plasma cells; 2) paraproteinemia; 3) radiographically-evident osteolysis; 4) light chain proteinuria. Alternatively, a postmortem diagnosis was based on the findings of multiple plasma cell neoplasms, with marrow involvement.

RESULTS

Sixteen cats were diagnosed with multiple myeloma between 1996 and 2004, with a median age of 14.0 years; 9 of 16 (56%) were castrated males, and 7 of 16 (44%) were spayed females. Laboratory abnormalities included hyperglobulinemia (14/16, 87.5%), with 11/14 (78.5%) monoclonal and 3/14 (21.4%) biclonal gammopathies; hypoalbuminemia (4/16, 25%); light chain proteinuria, (4/9, 44.4%); hypocholesterolemia (11/16, 68.7%); hypercalcemia, (3/15, 20%); nonregenerative anemia, (11/16, 68.7%); regenerative anemia, (1/16, 6.2%); neutropenia (5/15, 33.3%); thrombocytopenia (8/16, 50%); and marrow plasmacytosis (14/15, 93.3%). Plasma cells were markedly immature, atypical, or both in 10 of 12 (83.3%) cats. Focal or multifocal osteolysis was noted in 6 of 12 (50%) cats for which radiographs were available for review; generalized osteopenia was found in 1 (8.3%) cat. Noncutaneous, extramedullary tumors were found in all cats assessed, 7/7 (100%), including spleen (6), liver (3), and lymph nodes (4). The disease in 1 of 2 cats with cutaneous tumors progressed to plasmacytic leukemia.

CONCLUSIONS

Common findings in feline multiple myeloma include atypical plasma cell morphology, hypocholesterolemia, anemia, bone lesions, and multi-organ involvement. Based on the results of this study, we advocate modifying diagnostic criteria in cats to include consideration of plasma cell morphology and visceral organ infiltration.

Immunohistochemistry in bone marrow pathology: a useful adjunct for morphologic diagnosis

Pathomorphological examination of trephine biopsies of the bone marrow (BM) represents a standard method for the diagnosis and staging of hematologic neoplasms and other disorders involving the BM. The increasing knowledge about the genetic basis and biology of hematologic neoplasms, as well as the recently proposed WHO classification system, provide the framework for an accurate diagnosis. Although conventional morphology remains the gold standard for paraffin-embedded BM trephines, immunohistochemical stainings have become an integral part of the diagnostic workup. Antibodies suitable for paraffin sections are generally applicable to BM trephines, but modifications of staining protocols may be necessary due to the alternative fixatives and decalcification procedures used for BM biopsies. The indications for immunostainings range from confirmation and classification of lymphoma involvement, subclassification of acute leukemias, and estimating blast counts in myelodysplastic and myeloproliferative syndromes to characterization of BM involvement in nonhematologic neoplasms. Although subtyping of NHL in the BM is more difficult from the point of morphology, classification of the entities that frequently involve the BM, especially the small B-cell lymphomas, can easily be achieved with the help of immunohistochemistry. In this review, we try to summarize the current state of the art in BM immunohistochemistry for the diagnosis of hematologic disorders. Moreover, diagnostic algorithms and useful antibody panels are proposed for a rational and cost-effective approach.