Lethal tracheal dissolution during treatment for 1121 Figure 2 Portable chest radiograph after intubation to mention whether the tumour invaded the showing extensive trachea or larynx.4 In one report two patients subcutaneous emphysema demonstrated obstructive symptoms and bi- of the upper chest and opsy proven tracheal invasion by thyroid Thorax: first published as 10.1136/thx.50.10.1121 on 1 October 1995. Downloaded from neck. The cervical trachea is markedly distended lymphoma; both patients received chemo- (arrows). therapy with resolution ofobstruction and with- out tracheal perforation, and both were alive one and two years later without evidence of disease.5 Computed tomographic scanning is the re- commended method of assessment of extra- thyroid extension of lymphoma.' Early awareness of tracheal involvement by lymph- oma should alert the clinician to the remote possibility of tracheal dissolution during treat- ment of this extremely difficult clinical prob- lem. mon: hoarseness (9-67%), (9-60%), 1 Randall J, Obeid ML, Blackledge GR. Haemorrhage and perforation of gastrointestinal neoplasms during chemo- and dyspnoea or stridor (9-35%).5 Although therapy. Ann R Coil Surg Engl 1986;68:286-9. the optimal treatment for thyroid lymphoma 2 Shaw JHF, Holden A, Sage M. Thyroid lymphoma. Br J Surg 1989;76:895-7. is uncertain, patients with stage IIE or more 3 Tupchong L, Hughes F, Harmer CL. Primary lymphoma of advanced disease should probably receive the thyroid: clinical features, prognostic factors, and results oftreatment. IntjRadiat OncolBiolPhys 1986;12:1813-21. chemotherapy in addition to local treatment 4 HamburgerJI, MillerJM, Kini SR. Lymphoma ofthe thyroid. (surgery and/or radiotherapy).6 Ann Intern Med 1983;99:685-93. 5 Van Ruiswyk J, Cunningham C, Cereletty J. Obstructive Perforation ofthe gastrointestinal tract at the manifestations ofthyroid lymphoma. Arch Intern Med 1989; site of disease in patients with gastrointestinal 149:1575-7. 6 Vigliotti A, Kong JS, Fuller LM, Velasquez WS. Thyroid lymphoma who are receiving chemotherapy has stages IE and IIE: comparative results for been well described;' a similar perforation has radiotherapy only, combination chemotherapy only, and multimodality treatment. IntJ Radiat Oncol BiolPhys 1986; been reported in a patient with thyroid lymph- 12:1807-12. oma metastatic to the small bowel.7 7 McDermott EWM, Cassidy N, Heffeman SJ. Perforation through undiagnosed small bowel involvement in primary Lethal tracheal perforation during chemo- thyroid lymphoma during chemotherapy. 1992;69: therapy has not previously been described in a 572-3. 8 Takashima S, Morimoto S, Ikezoe J, Arisawa J, Hamada S, patient with primary thyroid lymphoma. Most Ikeda H, et al. Primary thyroid lymphoma: comparison of series of patients with thyroid lymphoma fail CT and US assessment. Radiology 1989;171:439-43. http://thorax.bmj.com/ Thorax 1995;50:1121-1123

found in the anterosuperior compartment. Commentary: Thymomas are the most common tumour in this region and lymphomas and carcinoids may lymphoma involving involve the thymus. Mediastinal germ cell tu- mours are located in the anterosuperior com- the partment and thyroid tumours may involve on September 30, 2021 by guest. Protected copyright. the upper part of the superior mediastinum. challenges in diagnosis Secondary tumours, particularly bronchogenic carcinoma, should also always be considered. and management Thymomas are often suspected by their radio- logical appearance and they may have as- sociated systemic features, most notably myasthenia gravis. They are usually treated Jonathan A Ledermann by surgical extirpation which allows further detailed study of the pathology and avoids the Lymphomas are the seventh most common increased incidence of local recurrence seen if malignancy and the incidence of non-Hod- needle biopsy is performed before surgery. For gkin's lymphoma is increasing. Correct diag- other masses radiologically guided needle bi- nosis is important as they are treatable and, in opsy has become commonplace and has re- some cases, curable. Lymphomas can involve duced the need for operative biopsy. Fine any organ system and, as thoracic involvement needle aspiration is simple and may be sufficient is common, they often present to respiratory to diagnose a carcinoma. However, as Robinson physicians. The diagnosis is not always straight- et al point out, the diagnosis of lymphoma may forward and treatment is complex. The case be missed unless adequate tissue is removed. Department of reports in this issue of Thorax illustrate some This is required for study of the morphology , of the diagnostic and therapeutic problems as- of the tumour which provides prognostic in- University College sociated with this disease. formation and assists management. A com- London Medical Mediastinal tumours in adults are School, divided prehensive immunohistological examination London WIP 8BT fairly equally throughout the mediastinal com- should be performed in case misleading in- J A Ledermann partments. Approximately 40% of tumours are formation is obtained from one immuno- 122 Ledermann histochemical method. Some "anaplastic Cysts in the thymus such as those described carcinomas" turn out to be high grade non- by El-Sharkawi and Patel may be found when Hodgkin's lymphomas which are potentially this gland is the principal site of involvement curable.' Tumour-specific chromosomal ab- with Hodgkin's disease. Whether Hodgkin's Thorax: first published as 10.1136/thx.50.10.1121 on 1 October 1995. Downloaded from normalities have been identified in several types disease originates in the thymus in these cases of lymphoma, germ cell tumours, Ewing's sar- is not clear, but management is similar to me- coma, and peripheral neuroepithelioma. The diastinal Hodgkin's disease. diagnostic usefulness of this technique is likely A significant number of non-Hodgkin's to increase as further abnormalities are iden- lymphomas arise in extranodal sites. Their clin- tified. Raised serum tumour markers such as ical behaviour is related more to their biology oa-fetoprotein and human chorionic gonado- than to their anatomical location. Thyroid trophin may help to support a histological diag- lymphomas are rare and account for about nosis of a mediastinal germ cell tumour. Rarer 5% of thyroid malignancies. They are usually tumours such as the "atypical syn- associated with Hashimoto's thyroiditis and drome" should be considered if a rapidly grow- occur most commonly in women. Many are ing undifferentiated carcinoma is found in a low grade tumours similar to MALT lymphoma predominantly midline distribution. This found in the gastrointestinal tract.4 Others are tumour, which occurs particularly in young intermediate or high grade B cell tumours. men, often responds well to intensive cisplatin Although they are often confined to the thyroid based chemotherapy.2 and cervical lymph nodes at presentation, tu- Most cases ofHodgkin's disease that occur in mours with aggressive type histology may dis- the mediastinum are of the nodular sclerosing seminate widely.' T cell lymphomas of the type. The choice between primary chemo- thyroid are rare so that other sites of origin therapy and radiation is usually made on the should be considered, particularly as the patient basis of tumour stage and bulk of the disease. described by Melnyk et al had axillary lymph- A good clinical and radiological response to adenopathy and skin involvement. The tumour treatment occurs in most patients, but radio- in the patient they described had many char- logical abnormalities may persist with widening acteristics similar to those seen in peripheral T ofthe mediastinum and architectural distortion cell lymphomas ofthe angiocentric type. These of the lymph node areas. It is often impossible are aggressive tumours, associated with nec- to know whether there is persistent active rosis, and can involve the mediastinum and Hodgkin's disease. This creates a dilemma as lung. Tumours of the nasopharynx were for- consolidation treatment with radiotherapy may merly and appropriately called "lethal midline be required but it increases the chance of long granuloma". They behave as a locally de- term toxicity. An example of this problem is structive inflammatory tumour and evolve into presented in the report by Thomas et al. BCNU a generalised T cell lymphoma. They are known

(carmustine) is one of a group of chemically to produce a coagulative necrosis6 and the case http://thorax.bmj.com/ unrelated drugs (others include bleomycin, described by Melnyk et al probably falls into busulfan, methotrexate, in this category. The destructive lesion they high doses, and mitomycin C) known for their described is dissimilar from the more widely damaging effects on lung. The probability of recognised "tumour lysis" syndrome, oc- pulmonary injury increases when radiotherapy casionally seen shortly after the start of chemo- is given to the lung, either before or after therapy for leukaemia and lymphomas. Rapid cytotoxic chemotherapy.3 Dry cough and dys- dissolution oftumour is usually associated with pnoea are the characteristic symptoms of acute a gross metabolic disturbance such as lactic pneumonitis due to cytotoxic drugs or ra- acidosis, hyperkalaemia, hyperphosphataemia, on September 30, 2021 by guest. Protected copyright. diation. Drug-related damage often causes and hyperuricaemic renal failure. These com- changes in the basal respiratory segments with plications can often be avoided by careful pre- linear and nodular shadowing which may be- paration of the patient before chemotherapy, come confluent on the chest radiograph. Severe ensuring that there is adequate hydration and respiratory insufficiency does sometimes occur, inhibition of uric acid synthesis. In solid tu- but prompt treatment with high dose steroids mours, such as germ cell malignancies or gest- often reverses the process. Steroids are less ational trophoblastic tumours, rapid cytolysis effective in chronic progressive drug-induced of extensive pre-existing pulmonary metastases fibrosis. The decision to consolidate treatment may lead to respiratory decompensation. It may with radiation therapy is usually made on clin- be possible to lessen this effect by initiating ical grounds. A biopsy sample ofresidual tissue chemotherapy at a lower than usual dose. after treatment is subject to sampling error; Correct diagnosis of mediastinal tumours is additional imaging by gallium or positron em- important and their investigation is best per- mission tomographic scanning is only some- formed by a multidisciplinary specialist team times helpful in distinguishing tumour from of surgeons, pathologists, oncologists, and residual non-malignant tissue. The risk oflocal radiologists. Lymphoma and Hodgkin's disease relapse is much greater when a lymphoma oc- are curable in some patients and treatment in cupies more than one third of the width of the others results in prolonged survival. However, mediastinum although it can be reduced by the complications of treatment and emergence radiotherapy. However, the addition of radio- of drug resistance illustrate some of the frus- therapy has not been shown to improve overall trations of treatment. survival in this group of patients. About half the cases ofHodgkin's disease have mediastinal 1 Gatter KC, Alcock C, Heryet A, Mason DY. Clinical import- involvement which may include the thymus. ance of analysing malignant tumours of uncertain origin Lymphoma involving the mediastinum 1123

with immunohistochemical techniques. Lancet 1 985;i: 4 Isaacson PG, Androulakis PA, Diss TC, Pan L, Wright DH. 1302-5. Follicular colonization in thyroid lymphoma. Am J Pathol 2 Hainsworth JD, Wright EP, Gray GF, Greco FA. Poorly 1991;141:43-52. differentiated carcinoma of unknown primary site: cor- 5 Tsang RW, Gospodarowicz MK, Sutcliffe SB, Sturgeon JF, relation of light microscopic findings with response to Panzarella T, Patterson BJ. Non-Hodgkin's lymphoma of cisplatin-based chemotherapy. J Clin Oncol 1987;5: 1275- the thyroid gland: prognostic factors and treatment out- Thorax: first published as 10.1136/thx.50.10.1121 on 1 October 1995. Downloaded from 80. come. The Princess Margaret Hospital Lymphoma Group. 3 Collis CH. Chemotherapy-related morbidity to the lungs. In: Int J Radiat Oncol Biol Phys 1993;27:599-604. Plowman PN, McElwain T, Meadows A, eds. Complications 6 Chan JK, Ng CS, Lau WH, Lo ST. Most nasal/naso- of cancer management. Oxford: Butterworth Heinemann, pharyngeal lymphomas are peripheral T-cell neoplasms. 1991:250-71. Am J Surg Pathol 1987;11:418-29.

Thorax 1995;50:1123-1124

obstructive apnoeas in some but not all patients (two out of six); both were snorers Chest physiotherapy in LETTERS TO and had macroglossia. Four patients had cystic fibrosis central apnoeas only. This predominance of THE EDITOR central events would agree with the data pub- I am concerned that the paper by Miller et lished several years ago by Smith et al.2 How- al (February 1995;50:165-9) is not a valid ever, as correctly pointed out by both Smith comparison of autogenic drainage and the et al and Khan and Heckmatt, obstructive active cycle of breathing techniques (ACBT) apnoeas can be mistakenly identified as cen- as stated. tral (the so-calledpseudocentralapnoeas) when ACBT is a method of physiotherapy which Guidelines for care during the weak respiratory muscles cannot move includes thoracic expansion exercises, breath- the thorax against a narrowed or closed upper ing control, and the forced expiration tech- bronchoscopy airway. To classify such events properly, nique (FET). The FET is an important oesophageal pressure recordings are re- component combining forced expiration Guidelines for care during bronchoscopy commended. Neither Khan and Heckmatt, (huffing) and breathing control. Several huffs were agreed by the British Thoracic Society Smith et al, nor ourselves used this method. to low lung volume interspersed with breath- in January 1993.' A retrospective audit of However, Quera-Salva et alr used oesophageal ing control are often needed before secretions adherence to these guidelines in Scotland was pressure recording to study sleep respiratory are mobilised from the smaller peripheral performed for 23 hospitals by means of a disturbances in patients with myasthenia airways to the larger airways.' 2 It is only written questionnaire and the results were gravis. Although this is a different disease, it when the secretions have reached the larger presented at a recent meeting of the Scottish is interesting to note that, with this gold proximal airways that the huff from high lung Thoracic Society. standard technique, most of the respiratory volume is required. The forced expiration Of the 33 respiratory consultants who re- events at night were of central origin.3 We technique described in the paper of Miller et plied to our survey, 31 routinely applied pulse therefore believe that the conclusion of Khan al is similar to that above, but there is very oximetry during bronchoscopy, 31 wore and Heckmatt, that most of the apnoeas in good reason to believe that the actual method gloves, but only eight wore a gown, four a patients with Duchenne muscular dystrophy performed by the patients was "one hufffrom mask, and three goggles during the procedure, were obstructive, has to be validated using mid to low lung volume followed by another despite recommendations that mask, gown, appropriate methodology. Their conclusion huff at a higher lung volume." Whilst this gloves, and close fitting eye protection should is also weakened by the fact that the sleep difference may appear subtle, to a physio- be worn in all cases. Resuscitation equipment studies were carried out at home in a non- therapist and patient it is a major difference was available in the bronchoscopy suite in 31 supervised fashion and were analysed in a in technique and does not correspond with http://thorax.bmj.com/ cases, and in all but one case a nurse or second semi-automatic way. This approach would be the technique previously described in the lit- doctor was present during the procedure. a valuable one in screening or epidemiological erature.'13 Twenty eight consultants reported that their studies but it is probably not appropriate The statement that the two treatment re- bronchoscopy nurses adhered to the policy for pathophysiological research. To obtain gimens used in this study were equally as of the BTS Working Party on Infection Con- accurate and reproducible data such studies good is not in dispute, but the claim that trol.2 In 30 of the 33 replies ECG monitoring have to be performed under supervision and one of the regimens was ACBT is cause for was available for patients with known cardiac to be manually scored.12 It is important to concern. If my belief is correct, this study problems, and in all cases antidotes were clarify the nature of the sleep respiratory was not a true comparison between ACBT available for potentially respiratory de- and autogenic drainage. The results are likely events in patients with Duchenne muscular on September 30, 2021 by guest. Protected copyright. pressant drugs. In general, adherence to the dystrophy because it may have therapeutic to mislead medical practitioners, physio- BTS guidelines on care during bronchoscopy implications. If the most predominant re- therapists, and patients and could in- is satisfactory, but in view of non-compliance spiratory event is obstructive apnoea, nasal appropriately influence the direction offuture with the wearing ofmasks, gown and goggles, continuous positive airway pressure (CPAP) research. Further studies are required to pro- these components need to be re-addressed. should be effective. CPAP is cheaper and vide a valid comparison between these two techniques. E A MILLAR easier to use than intermittent positive vent- P d'A SEMPLE ilation, which nowadays constitutes the treat- Department of General Medicine, ment of choice for patients with Duchenne BARBARA A WEBBER Inverclyde Royal Hospital, muscular dystrophy and . Physiotherapy Department, Greenock PA16 OXN, UK Royal Brompton Hospital, London SW3 6NP, UK 1 Harrison BDW. Guidelines for care during bron- choscopy. Thorax 1993;48:584. F BARBE 2 Woodcock A, Campbell I, Collins JVC, Hanson M A QUERA-SALVA 1 PryorJA, Webber BA. An evaluation ofthe forced P, Harvey J, Corris P, et al. Bronchoscopy and A G N AGUSTI expiration technique as an adjunct to postural infection control. Lancet 1989;ii:270-1. Servei de Pneumologia, drainage. Physiotherapy 1979;65:304-7. Hospital Univ. Son Dureta, 2 Pryor JA, Webber BA, Hodson ME, Batten JC. 07014 Palma de Mallorca, Evaluation of the forced expiration technique Spain as an adjunct to postural drainage in treatment of cystic fibrosis. BMJ 1979;2:417-8. in Duchenne 3 Pryor JA, Webber BA, Hodson ME. Effect of Apnoea chest physiotherapy on oxygen saturation in muscular dystrophy 1 Barbe F, Quera-Salva MA, McCann C, Gajdos patients with cystic fibrosis. Thorax 1990;45: Ph, Raphael JC, de Lattre J, et al. Sleep re- 77. spiratory disturbances in patients with Du- Drs Khan and Heckmatt (February 1994;49: chenne muscular dystrophy. Eur RespirJ7 1994; 157-6 1) concluded that "sleep related breath- 7:1403-8. AUTHORS' REPLY In the first draft ofthe paper 2 Smith PEM, Calverley PMA, Edwards RHT. ing abnormality in Duchenne muscular dys- Hypoxemia during sleep in Duchenne mus- the description of ACBT differed from the trophy is initially obstructive . . .". We have cular dystrophy. Am Rev Respir Dis 1988;137: published version. The forced expiratory recently performed a night time study of six 884-8. technique was described as "one huff from 3 Quera-Salva MA, Guilleminault C, Chevret S, mid to low followed another patients with Duchenne muscular dystrophy Troche G, Fromageot C, McCann C, et al. lung volume, by and reached somewhat different conclusions.' Breathing disorders during sleep in myasthenia huff at a higher lung volume. Patients were Like them, we also observed predominantly gravis. Ann Neurol 1992;31:86-92. encouraged to cough and expectorate only if