Bone marrow biopsy in the evaluation of lymphoma, carcinoma and granulomatous disorders

Finite element simulation of multilayer model to simulate fine needle insertion mechanism into iliac crest for bone marrow biopsy

The main aim of this work is to use a finite element technique (FEM) to gain understanding about the bone marrow biopsy (BMB) needle insertion process and needle-tissue interactions in the human iliac crest. A multi-layer iliac crest model consists of stratum corneum, dermis, epidermis, hypodermis, cortical, and cancellous bone has been established. This paper proposes a FE model that examines all phases of tissue deformation, including puncture, cutting, needle-tissue interaction, and various stress-strain values for BMB needle during interaction. The results explain the needle-tissue interface and show the potential of this technique to estimate bone damage and tissue deformation for multiple needle dimensions, coefficient of friction, and penetration speeds. The insertion and extraction force of conical-shaped needles in the multi-layered iliac crest model decreased by 18.92% and 37.5%, respectively, as the needle diameter reduced from 11 G to 20 G. It has also been found that the significant insertion motion raises the deformation of the tissue due to the augmented frictional forces but reduces the strain perpendicular to the penetration direction closer to the needle tip. The simulation outcomes are helpful for the optimal design of fine biopsy needles used to perform the bone marrow biopsies.

Bone Marrow Collection: Comparison of Unassisted vs Assisted Bedside Collections by a Laboratory Technologist

OBJECTIVES

Bone marrow collections are often difficult, and creating quality smears and touch preparations at the bedside can prove challenging. The objective of this study is to compare the quality of bone marrow specimens between unassisted and assisted bone marrow collections by a bone marrow technologist.

METHODS

Data for this study were collected from 422 hematopathology reports over 14 months. We recorded the bone marrow quality of the different parts (aspirate smears, touch imprints, core biopsy, and clot/particle sections) as adequate, suboptimal, or inadequate. Student t test statistical analysis was performed between the corresponding parts in the two groups.

RESULTS

Our results demonstrate that the quality of assisted bone marrow specimens is significantly better compared with unassisted specimens, particularly for the aspirate smears (P < .0001) and touch imprints (P < .0001). Notably, the quality of aspirate smears was improved, which is important for cytologic evaluation.

CONCLUSIONS

We conclude that assistance by a bone marrow technologist resulted in a significant improvement in the quality of bone marrow collection.

Bone marrow involvement in sarcoidosis: an elusive extrapulmonary manifestation

Sarcoidosis is a granulomatous disease with various extrapulmonary manifestations. We describe a 51-year-old African American woman with a history of cutaneous sarcoidosis admitted with bicytopenia. Suspicion for systemic sarcoidosis was established after contrast-enhanced computerized tomography of the chest, abdomen and pelvis showed a pulmonary nodule, diffuse lymphadenopathy and hepatosplenomegaly. Cytopenias in sarcoidosis, when present, may reflect bone marrow infiltration. Hence, biopsy was obtained and bone marrow sarcoidosis was diagnosed. This manifestation, in spite of ethnic and gender predilection, is rarely seen. As with other forms of sarcoidosis, treatment comprises of corticosteroids.

Abbreviations: ANCA: Antineutrophil cytoplasmic antibody; BM: Bone marrow; BMS: Bone marrow sarcoidosis; CT: Computerized tomography; HIV: Human immunodeficiency virus; HLA: Human leukocyte antigen; MRI: Magnetic resonance imaging

Clinical Relevance of Bone Marrow Biopsy in Staging and Follow-Up of Breast Cancer

Bone marrow biopsies by Jamshidi needle were performed in 106 breast cancer female patients. Sixty-four of them were in follow-up after mastectomy, and neoplastic involvement of marrow was found in 21 patients (32.8%). Among the 42 women undergoing staging before mastectomy, the incidence of marrow involvement was 11.9% (5 women, all with radiographic positivity). Of the 37 women, either in follow-up or in the staging phase, with bone metastases detected by roentgenographic and isotopic examination, the bone biopsy was positive in 23 (62.1%), and 7 histologically had micrometastases. Three women, without any radiographic or isotopic sign of metastases, had positive biopsies. A good correlation was found between the hydroxyproline:creatinine ratio and neoplastic involvement of bone marrow.

Accuracy and Relative Value of Bone Marrow Aspiration in the Detection of Lymphoid Infiltration in non-Hodgkin Lymphoma

Aims and background

In hematologic malignancies, bone marrow aspiration is considered complementary to bone marrow biopsy for the detection of tumor infiltration. The present study evaluated the accuracy of bone marrow aspiration and the relative contributions of bone marrow aspiration and bone marrow biopsy in detecting bone marrow involvement by non-Hodgkin lymphomas.

Methods and study design

We compared 51 simultaneous marrow aspirates and core biopsies from non-Hodgkin lymphoma patients for sensitivity, specificity, concordance, quality and clinical relevance.

Results

The agreement level of bone marrow biopsy and bone marrow aspiration was 80%, and the overall sensitivity and specificity for bone marrow aspiration were 69% and 86%, respectively. When considering only the indolent non-Hodgkin lymphoma samples, the sensitivity of bone marrow aspiration was 82% and the specificity was 85%, whereas the sensitivity and specificity were 40% and 86%, respectively, in the aggressive non-Hodgkin lymphoma specimens. Five cases (10%) were reported in which bone marrow biopsy did not detect lymphoid infiltration even though the bone marrow aspiration was positive. In one of these, lymphoid infiltration was documented by a second bone marrow biopsy performed thereafter.

Conclusions

The data from the current study show that bone marrow aspiration is a useful procedure with which to detect bone marrow infiltration by lymphoma. Although it cannot be a substitute for examination of the marrow by core biopsy, the utility of adding an aspirate to bone marrow biopsy is supported by its earlier and easier availability for bone marrow examination, the larger amounts of marrow that can be examined with both procedures, and the percentage, although small, of potentially true-positive bone marrow aspirates with negative biopsies.

Bone marrow solid core biopsy needle: a critical assessment of the utility, benefits and limitations of the instruments employed in current day haematology and oncology

The optimal clinical evaluation of the bone marrow requires an examination of air-dried and well-stained films of the aspirated tissue along with a histopathological evaluation of adequately processed and properly stained core biopsy specimens. A bone marrow evaluation can be essential in establishing a diagnosis, determining the efficacy of treatment in haematological disorders and to monitor haematological status of patients following bone marrow/stem cell transplantation. It is also an essential component of the staging process for newly diagnosed malignancies. Currently available bone marrow aspiration needles are quite satisfactory and if properly used provide good-quality specimens for morphological evaluation. However, if a bone marrow core biopsy is concerned, several needles are currently in use but not all of them provide good-quality biopsy specimens for histological evaluation or are user friendly. We have compared the recently introduced Moeller Medical single use bone marrow core biopsy needle with the Jamshidi needle with marrow acquisition cradle (CareFusion), J-needle (Cardinal Health) and OnControl device (Vidacare). It is concluded that the Moeller Medical needle system has definite advantages over others and is recommended for routine use.

Comparison between 1-needle technique versus 2-needle technique for bone marrow aspiration and biopsy procedures

CONTEXT

Bone marrow examination is essential for diagnosis and staging of hematologic disorders. Traditionally, the bone marrow biopsy and aspirate are obtained with 2 needles at 2 separate sites. This approach is associated with significant discomfort, procedural time, and occasionally, morbidity. Although previous observations had suggested that a single-needle technique at one site is a simpler and less-painful procedure, there had been concern that the 1-needle technique may yield a suboptimal biopsy for diagnosis.

OBJECTIVE

To conduct a systematic comparison of multiple parameters of bone marrow biopsy specimens obtained by the traditional 2-needle technique versus the 1-needle technique for bone marrow collection.

DESIGN

We retrospectively evaluated 20 biopsy specimens obtained by each of the 2 mentioned techniques by comparing the morphologic quality of the biopsy, biopsy length, and biopsy cellularity.

RESULTS

We found that the 1-needle technique yielded an adequate biopsy for diagnosis. The measured parameters of the samples obtained by the 1-needle versus 2-needle techniques were similar.

CONCLUSION

This study suggests that the 1-needle technique may be preferred for bone marrow aspirate and biopsy.

Relative value of sternal aspiration, iliac crest biopsy and biopsy imprint in the diagnosis of secondary cancer involvement of the bone marrow

Sternal aspirates, iliac crest biopsies and biopsy imprints from 31 patients with verified metastatic cancer to bone marrow were reviewed. All three methods were shown to be complementary, as cancer cell deposits were detected in some cases by one procedure and missed by the others.

Bone marrow aspiration before bone marrow core biopsy using the same bone marrow biopsy needle: a good or bad practice?

A single-needle single-site technique for bone marrow aspiration and core biopsy has been compared with a two-needle technique, using 30 randomly selected patients who required these two investigations. In addition, two single-needle techniques were compared, aspirating immediately after penetrating the cortex or, alternatively, aspirating after the needle (without the stilette) had been advanced 20-25 mm. The two-needle technique was found to be superior to either of the single-needle techniques, which often resulted in a biopsy specimen that was denuded of bone marrow cells.

Infiltrative myelopathy by paracoccidioidomycosis. A review and report of nine cases with emphasis on bone marrow morphology

AIMS

To report nine additional well-defined cases with infiltrative myelopathy by paracoccidioidomycosis (PCM), to describe the specific lesions and infection-related stromal abnormalities, to review the literature on this type of involvement and to introduce a new cause of granulomatous lesions of bone marrow.

METHODS AND RESULTS

Different bone marrow specimens were studied (aspirated smears, aspirated clots, biopsy imprints and biopsies) from nine patients with acute or subacute forms of PCM known to have PCM infiltrative myelopathy.

CONCLUSIONS

The biopsy specimens were the best for demonstrating bone marrow involvement by PCM. The lesions varied from compact and focal granulomas with few fungal cells to numerous disseminated fungal cells within a loose granulomatous inflammatory reaction, with a continuum between these extremes suggesting a spectrum of immune response to the fungi. Other findings such as bone marrow fibrosis, parenchymal coagulative necrosis and bone necrosis were also observed in the affected areas.

A new single-use bone marrow biopsy needle

A new needle for taking a bone marrow biopsy sample from the posterior iliac crest is described. The needle comprises a hollow tube having a front-end portion formed to a reduced diameter. The front end is tapered by means of circumferentially spaced facets, forming a cutting edge. A series of flutes/serrations are introduced at the tapering transitional portion, between the main wider portion of the hollow tube and its reduced-diameter front-end portion. This design is new and is not available in any other conventional biopsy needle. These serrations help in its penetration through the hard cortical bone. A spacer guide, which is placed between the plastic dome of the needle and the stilette cap to enhance the ergonomics, is also new. The inside of the spacer guide is funnel shaped, through which the stilette is passed, thereby ensuring an easy and accurate alignment of the distal ends of the hollow needle and the stilette. This technique facilitates removal of the biopsy sample rearwardly out of the hollow needle particularly when the mouth (distal-end opening) of the needle is covered by extraneous bony soft tissue. In this technique, the same stilette that occupies the needle during its entry into the marrow cavity is used in sample removal. Thus, the need for an additional pusher to remove the biopsy sample from within the lumen of the needle has been eliminated.

Bone marrow metastases. A review

Although bone marrow examination is a common procedure in the evaluation of patients with cancer, its role and contribution have been questioned in recent years. This review deals with the clinical and biologic aspects of metastasis to the bone marrow. The discussion is focused on the common tumor types that involve marrow and the application of newer techniques for tumor detection in the marrow. Therapeutic and prognostic implications of bone marrow metastasis are significant in several clinical settings. The mechanisms by which tumor cells affect marrow function have not been completely defined.

Fever of unknown origin in the elderly. A sequential approach to diagnosis

Elderly patients with persistent unexplained fever require a diagnostic evaluation that focuses on specific infections (eg, occult abdominal abscess, bacterial endocarditis, miliary tuberculosis), rheumatic disorders (eg, temporal arteritis, polyarteritis nodosa), and neoplasms (eg, lymphoma, nephroma). Assessment is directed by the subtle clues elicited from meticulous, repeated history taking and physical examination. Therapeutic trials or exploratory laparotomy may be appropriate but should not be attempted out of a sense of frustration.

Significance of granulomas in bone marrow: a study of 40 cases

Granulomas in bone marrow are an infrequent finding related to diverse disease. We reviewed 8057 bone marrow studies made over a period of 10.5 years, confirming the presence of granulomas in 40 patients. Global incidence was 0.50% and annual incidence 3.80 cases/yr. Because of the non-specificity of the morphological data, the diagnostic significance of the finding is limited, but it does serve to narrow the field of etiological possibilities. Associated disease was demonstrated in 82.5%, infectious diseases being the most common (tuberculosis, brucellosis, typhoid fever and kala-azar). Two previously unpublished entities are introduced: refractory anemia with excess blast cells (dysmyelopoietic syndrome) and malignant histiocytosis. 3 patients presented human immunodeficiency virus infection, the etiopathogenic role of this retrovirus in the generation of granulomas being unknown. The efficacy of bone marrow study in demonstrating granulomas increases if both the aspirate clot and bone cylinder are examined.

Value of long-core biopsy in the detection of discrete bone marrow lesions

A series of 256 bone marrow biopsy specimens was obtained at different times from a group of patients with acute myeloid leukaemia, chronic granulocytic leukaemia and acute lymphoblastic leukaemia, and was analysed in parallel with peripheral blood smears and bone marrow aspirate samples. In five of these biopsy specimens the bone marrow lesion was discrete, deeply seated within the marrow cavity and detected only in long-core biopsies. Neither peripheral blood nor bone marrow aspirates obtained at the same time established the correct diagnosis. This suggests that when peripheral blood and bone marrow aspirate samples fail to indicate the diagnosis a long-core biopsy may yield positive results.

Stromal cell effects on clonal growth of tumors

Clonal growth of tumor cell lines originating from a variety of solid tumors was studied. The seeding efficiency of these tumors in methylcellulose medium was in the range of 0.036 to 0.177. Stromal cell lines from mouse bone marrow as well as primary stromal cells from human bone marrow stimulated the growth of HCT and oat human carcinoma cells 32-fold and 25-fold, respectively. In contrast, these stromal cells inhibited the in vitro cloning of human and mouse sarcoma cell lines. Both activities of the stromal cells diffused through agar layers and operated across species barriers. Despite the diffusable nature of the factors involved, no biologic activity was observed in concentrated conditioned media prepared in the presence or absence of serum. Human foreskin fibroblasts tested under identical conditions, could neither stimulate nor inhibit the clonal growth of tumors. This preferential growth of tumor cells in the presence of tissue specific stroma may be used as an in vitro model for the study of the role of stromal cells in tumor cell spread.

New instrument for longitudinal hemisectioning of undecalcified marrow cores, for simultaneous processing and examination with useful and complimentary techniques

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Successful therapy of sarcoidosis-associated thrombocytopenia refractory to corticosteroids by a single course of human gammaglobulins

Thrombocytopenia developed in a 21-year-old patient with sarcoidosis when corticosteroid therapy was discontinued. Platelet-associated IgGs were elevated. High-dose cortisone did not affect the thrombocytopenia. However, platelet counts remained normal for more than 1.5 years following intravenous treatment with a single course of human gammaglobulins.

Bone marrow morphologic changes after combination chemotherapy including VP-16

Bone marrow aspirates and biopsy specimens were examined from seven patients with small cell lung cancer. All patients had received recent combination chemotherapy including VP-16. No correlation between marrow biopsy cellularity and hematologic toxicity could be established. However, an unusual combination of morphologic changes was seen. This included an initial rapid increase in the M:E ratio, interference with cell division, and eventual cell death. There was little evidence of mitotic arrest or megaloblastosis. These changes are consistent with the known mechanism of action of VP-16, the only agent given to all patients. The small sample size and the unknown contributions of the other cytotoxic agents administered allow only limited conclusions.

Assessment of bone marrow histology in the malignant lymphomas (non-Hodgkin's): correlation with clinical factors for diagnosis, prognosis, classification and staging

Bone marrow biopsies of 678 untreated patients with established malignant non-Hodgkin's lymphomas (ML) were investigated. The bone marrow was involved in 468 cases, an overall frequency of 69%. The Kiel classification of the ML (based on lymph node histology) was applied and the biopsies were classified: ML lymphocytic 36%, ML 'hairy cell' 24%, ML lymphoplasmacytic/cytoid 24%, ML centrocytic 6%, ML centroblastic/centrocytic 4%, ML lymphoblastic (without ALL) 3%, ML centroblastic 2% and ML immunoblastic 1%. The life tables of the patients were similar whether classified according to the histology of the lymph node or the bone marrow. A multivariate computer based analysis of both clinical and histological data was performed to test their prognostic relevance. The cell type, the proliferation pattern and the extent of infiltration in the bone marrow all proved to be factors of prognostic significance. The results indicate that classification of the ML based on lymph node histology is applicable to the bone marrow, is reproducible and has prognostic significance. Consequently, a bone marrow biopsy is a useful clinical tool for staging and for histological classification of patients with ML.

A new bone marrow biopsy needle with core securing device

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Multiple histologic subtypes of non-Hodgkin's lymphoma: clinical and pathologic features

Twenty patients with non-Hodgkin's lymphoma (NHL) had different histologic subtypes of NHL in multiple sites or in a single tumor mass either at the time of their initial biopsy and staging (13 patients) or in the course of their disease (seven patients). These 20 cases represent 3.7% of all patients with NHL seen at the University of Chicago between January 1968 and May 1979. The five-year actuarial survival rate for all 20 patients was 68%. For those 13 patients who had multiple histologic subtypes at the initial workup, the five-year survival rate was 45%; for the seven patients who developed a new histologic subtype later in the course of the disease, the five-year survival rate was 85%. In the latter group of patients, however, the initial biopsy specimens demonstrated better prognostic subtypes, and the median survival from the time of diagnosis of a new, less favorable histologic subtype averaged only four months. These findings indicate that the prognosis is related to the least favorable histologic subtype present, unless this is only a minor component of a composite lymphoma or is limited to one extranodal site.

Value of imprint preparations of bone marrow biopsies in hematologic diagnosis

Imprint preparations were performed on bone marrow biopsy specimens obtained from the posterior superior iliac spine of 310 consecutive patients. Bone marrow aspiration was attempted prior to biopsy. When aspiration was impossible or inadequate, imprint preparations were used in order to study cytologic detail and enhance interpretation of the biopsy specimen. Malignant infiltrates were present in 22 (7.1%) of the 310 biopsy specimens including: non-Hodgkin's lymphoma, 12 patients, metastatic carcinoma, 6; Hodgkin's disease, 1; multiple myeloma, 1; Waldenstrom's macroglobulinemia, 1; and Sezary's syndrome, 1. An aspirate could not be obtained in 8 (36%) of 22 cases, but malignant cells were found in imprint preparations of the biopsy specimens. This study demonstrates that imprint preparations of bone marrow biopsies are useful in evaluating patients with malignancy when bone marrow aspiration is inadequate.

Bone marrow biopsy in children: a study of 111 patients

Closed trephine needle biopsy of the bone marrow has become an established procedure in the evaluation of many malignant and benign diseases in adults; however, its role in pediatric pathology has not yet been defined. In the period from February 1974 to April 1978 we have performed 164 such biopsies in 111 children under 15 years of age. A representative specimen has been obtained in over 80% of cases. This series included, in order of frequency, non-Hodgkin lymphomas, Hodgkin lymphomas, aplastic anemias, rhabdomyosarcomas, neuroblastomas, miscellaneous solid tumors, and single cases of histiocytosis X, malignant histiocytosis, sarcoidosis, malignant histiocytoma, and Castleman lymphoma of the hyaline-vascular type. Histology has been found superior to cytology in the detection of neuroblastoma invasion; the evaluation of the true cellularity in aplastic anemia, and the detection of granulomatous tissue in the only case of sarcoidosis. In other diseases histology and cytology gave similar information, except for the few cases of acute leukemia in partial relapse, which has been better defined in the aspirate smears than in the core specimen. Further evaluation of this technique in other patient series appears advisable.

The value of preoperative screening procedures in stage I and II malignant melanoma

Fifty patients with melanoma (30 with clinical Stage I disease and 20 with clinical Stage II disease) were analyzed retrospectively along with the screening test done prior to surgery. While the value of the chest X ray is unquestioned in preoperative screening, the same cannot be said of liver, brain, and bone scans. The bone marrow biopsy, however, done with a Janshidi needle was of value in detecting one patient with bone-marrow metastases who on examination had clinical Stage II disease and precluded surgery in this same individual. Therefore, we feel that in the preoperative scanning of patients with Stage I or Stage II human malignant melanoma, and especially in the latter, the bone-marrow biopsy should be done routinely in addition to a hematological profile, liver profile, and chest X ray.

Variables predictive of bone marrow metastasis

Metastasis to bone marrow, though frequently occult, is an important clinical finding. Variables which correlate with carcinoma metastatic to bone marrow were studied retrospectively in 103 patients with malignancy whose bone marrow biopsies demonstrated metastatic disease. Sixty-six patients with metastatic cancer whose bone marrow biopsies were negative, served as controls. Since no single finding was diagnostic of marrow cancer, multiple variables were analyzed by stepwise discriminate analysis program. The four parameters which strongly correlated with marrow involvement were the leukoerythroblastic blood pattern, a serum lactic dehydrogenase over 500 IU/liter, a platelet count under 100,000/microliter and bone pain. Four parameters correlated less well and included a positive bone scan, hematocrit under 30%, uric acid over 10 mg/dl and blood urea nitrogen over 25 mg/dl. These data should help the clinician select those cancer patients with a high probability of marrow involvement.

Hodgkin's disease: problems of staging

The preferred histopathological classification of Hodgkin's disease (HD) is that suggested by Lukes and Butler as modified at the Rye Symposium; the histologic subtypes are highly reproducible and correlate well with the anatomic sites of involvement, clinical stage, and survival. The accuracy of the bipedal lymphangiogram, 67gallium scan, and ultrasonography in predicting abdominal involvement by HD is 90% , 50%, and 88%, respectively. Staging laparotomy remains the most accurate method of detecting intra-abdominal disease and has added immensely to new concepts in the management of HD. These concepts suggest that patients with nodal disease limited to the celiac axis or upper para-aortic areas (substage III1) or pathologic stage (PS) IIIS+N-A, when treated with extended field radiotherapy alone have survival rates comparable to PS IIA patients. In contrast, patients in PS IIIA with lower abdominal nodal disease (substage III2), regardless of splenic involvement, have a prognosis comparable to PS IV disease. Thus, there may only be two stages of HD, those curable with extended mantle or smaller radiotherapy fields alone, and those requiring chemotherapy with or without supplemental radiotherapy.

The role of bone marrow aspiration and biopsy in detecting marrow involvement by nonhematologic malignancies

A review of the records of the Memorial Sloan-Kettering Cancer Center identified 291 adult patients with nonhematologic malignancies who had undergone simultaneous bone marrow aspiration and biopsy from the same anatomic site. In 236 cases both samples were negative for tumor whereas in 39 both were positive. The biopsy was positive in three patients with a negative aspirate whereas in three others to aspirate was positive with a negative biopsy. The higher rate of tumor detection on aspirate in comparison with previous reports may be due to a thorough initial screening provided by technologists. Both aspiration and biopsy appear to be indicated for full evaluation of bone marrow in cancer patients.

[The significance of histologic assessment of the bone marrow in Hodgkin's disease]

The spreading of Hodgkin's disease in the bone marrow is of primary diagnostic significance in respect of its quantity as well as its quality, and therefore has to be taken into account from the initial staging procedure. The iliac crest is the most suitable site of the biopsy, the diagnostic significance of which depends on the adequate size of the specimen and on the technical standard of the histologic embedding with methacrylate, affording perfect semithin sections without decalcification. The prognostic value of the statement of Hodgkin's disease spreading in the marrow deserves further careful evaluation. A nonspecific reaction of the marrow against extramedullary lymphogranulomatosis closely resembling to the so-called tumor myeopathy has to be distinguished from the localized marrow changes due to the tumor itself. The former is depending primarily of the progress of the disease, the latter of its type as well. The well-known histologic classification covers the changes of the bone marrow due to Hodgkin's disease also. The different histologic types however exhibit a varying tendency of expansion within the bone. Generally the marrow involvement is accompanied with more severe clinical and hematological symptoms. The bone is altered mostly in the very region of the infiltration. This is not the consequence of direct tumorous destruction but of stimulation of environmental mesenchymal activities. Parenchymal and mesenchymal changes of the bone marrow, either directly or indirectly connected with the lymphogranulomatosis, are considered primarily as sequelae of the basic disease. The very close structural relationship between the original lymphogranulomatosus growth and these changes is one of the characteristics of Hodgkin's disease. As yet, there is no unequivocal pointer to structural characteristics whose appearance can exert an obstructive or stimulating effect on the lymphogranuloma tissue, apart from the number of lymphocytes and normal histiocytes in the specific infiltrate itself. Our observations of a special role of megakaryocytes in this connection deserve further attention.