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The inframammary fold: contents, clinical significance and implications for immediate breast reconstruction

      Abstract

      The amount of breast tissue within the inframammary fold (IMF) is controversial. Preservation of the IMF during mastectomy facilitates breast reconstruction and led some surgeons to practice conservation of the IMF, contrary to traditional descriptions of total mastectomy. The aim of this study was to analyse the clinical significance of IMF tissue content.
      A total of 50 IMF specimens were studied from 42 patients who underwent mastectomy between January 2001 and December 2002. The amount of breast tissue within each IMF was evaluated.
      The median patient age was 46 (range 33–86) years. The median body mass index was 23.4 (18.1–38.3) kg/m2. The median IMF volume resected was 2 (0.2–9.7) cm3 which was 0.6 (0.1–2.0)% of the breast volume. Ten specimens (20%) contained breast tissue and one (2%) contained breast tissue and an inframammary lymph node. Three specimens (6%) containing fibrofatty tissue without breast parenchyma had intramammary lymph nodes within the IMF. One patient (2%) who had a mastectomy for invasive ductal carcinoma had IMF tissue containing a lymph node within the IMF with breast cancer metastasis. The presence of breast tissue or lymph nodes within the IMF was unrelated to patient age, body mass index, the amount of IMF tissue in relation to breast volume and absolute breast size.
      Our finding that breast tissue and intramammary lymph nodes are present in 28% of IMF specimens requires re-consideration of the safety of preserving the IMF at mastectomy. If IMF tissue is resected and the immediate breast reconstruction is performed, the superficial fascial system should be reconstructed after excision of the IMF tissue in order to recreate the inframammary crease.

      Keywords

      The inframammary fold (IMF) is a zone of adherence of the superficial fascial system to the underlying chest wall. It is anatomically defined as the area where the skin of the lower pole of glandular breast tissue meets the chest wall forming a groove known as the inframammary crease.
      • Lockwood T.E.
      Superficial fascial system of the trunk and extremities: a new concept.
      The IMF consists of a ridge of dense nodular tissue forming an arc at the caudad circumferential edge of the breast. Here the mammary tissue is bound down tightly to the deep fascia of the thoracic wall, compressed between the anterior and posterior lamellae of the superficial fascia. The amount of breast within this structure has been variably defined.
      • Haagenson C.D.
      Diseases of the breast.
      • Muntan C.D.
      • Sundine M.J.
      • Rink R.D.
      • Acland R.D.
      Inframammary fold: a histologic reappraisal.
      Along its course, the IMF is positioned superficial to the anterior arch at the level of the fifth, sixth, seventh or eighth ribs. There is no predictable relationship between the inferior and lateral borders of the pectoralis major, the IMF or a specific rib.
      • Muntan C.D.
      • Sundine M.J.
      • Rink R.D.
      • Acland R.D.
      Inframammary fold: a histologic reappraisal.
      The recommendation to preserve the IMF during mastectomy to facilitate breast form at immediate breast reconstruction has been made by several authors.
      • Carlson G.W.
      Skin sparing mastectomy: anatomic and technical considerations.
      • Kroll S.S.
      • Ames F.
      • Singletary S.E.
      • Schusterman M.A.
      The oncologic risks of skin preservation at mastectomy when combined with immediate reconstruction of the breast.
      • Rand R.P.
      • Byrd D.R.
      • Anderson B.O.
      • Moe R.
      Skin sparing mastectomy with immediate tissue reconstruction.
      The incidence of breast cancer arising in the IMF is small and has been reported to be less than 2%.
      • Watson J.R.
      • Watson C.J.
      Carcinoma of the mammary crease: a neglected clinical entity.
      • Behranwala K.A.
      • Gui G.P.H.
      Breast cancer in the inframammary fold: is preserving the inframammary fold during mastectomy justified?.
      Carlson et al.
      • Carlson G.W.
      • Grossl N.
      • Lewis M.M.
      • Temple J.R.
      • Styblo T.M.
      Preservation of the inframammary fold: what are we leaving behind?.
      evaluated 24 IMF specimens and found that the mean volume of the IMF tissue excised was 99 (27.3–205.2) cm3. In that study, breast tissue was identified in 13 out of 24 specimens, comprising 0.04% by volume and 0.02% of all specimens of total breast tissue. The aim of this study was to analyse the clinical significance of IMF tissue in a larger consecutive series and to reconsider the oncologic concept of preserving the IMF during mastectomy to facilitate breast reconstruction.

      1. Patients and methods

      A total of 50 IMF specimens from 42 patients who underwent mastectomy were studied prospectively from January 2001 to December 2002. The indications for mastectomy are shown in Table 1. The IMF tissue was resected as a rim of tissue from within the inframammary crease that extended from the parasternal region to the mid-axillary line. One surgeon (G.G.) took all the specimens. Disruption of the complex superficial fascial system was minimised and the anterior and posterior lamella carefully repaired in breast reconstruction to recreate the IMF. The IMF tissue was submitted separately for detailed pathological assessment. The specimen was examined macroscopically and embedded in its entirety for histological examination. Breast tissue within the IMF was scored as absent, focally present or containing abundant breast tissue. The volume of the IMF tissue was calculated for a cuboid (length×breadth×height) and the volume of the breast was estimated as a cone (1/3πr2h). The Mann–Whitney test was used to compare the age, body mass index and percentage of IMF tissue to the presence or absence of breast tissue or lymph node within the IMF.
      Table 1Indications for mastectomy
      IndicationNo.
      A. Invasive breast cancer
       Invasive ductal carcinoma (IDC)18
       Invasive lobular carcinoma (ILC)4
       Mixed IDC and ILC1
       Apocrine carcinoma1
      B. Preinvasive carcinoma in situ
       Ductal9
       Ductal and lobular2
      C. Prophylactic mastectomy for risk-reduction (bilateral or contralateral)15
      Total50

      2. Results

      The median age of the patients was 46 (33–86) years. The median body mass index was 23.4 (18.1–38.3) kg/m2. The total volume of the specimens was calculated from the dimensions of the fresh tissue. The median breast volume was 330 (137–1246) cm3. In terms of volume, the median IMF resected was 2 (0.2–9.7) cm3 which was 0.6 (0.1–2.0)% of the breast volume.
      Ductal and glandular breast parenchyma with fibroadipose tissue was identified in 10 (20%) specimens. No primary breast cancer was identified in any of the IMF samples within breast parenchymal tissue. One IMF specimen (2%) contained a single intramammary lymph node and breast tissue. Breast tissue was absent in the remaining 39 (78%) specimens, which had only fibroadipose tissue (Table 2) . Three specimens had intramammary lymph nodes in fibrofatty tissue within the IMF (6%). One of the IMF specimens with a lymph node in fibrofatty tissue had evidence of metastasis in the intramammary lymph node. The presence of breast tissue or intramammary lymph nodes within the IMF was unrelated to body mass index, the amount of IMF tissue in relation to breast size, or absolute breast size.
      Table 2Inframammary fold tissue content in 50 specimens
      Breast specific tissue containing ductal and glandular parenchymaN (%)
      Absent breast tissue39 (78%)
       No intramammary lymph node tissue36 (72%)
       Intramammary lymph node present
      In one out of the three patients identified to have an intramammary lymph node in the IMF with no breast tissue, the inframammary node contained metastatic breast cancer.
      3 (6%)
      Focal breast tissue only1 (2%)
       No intramammary lymph node tissue1 (2%)
       Intramammary lymph node present0
      Abundant breast tissue10 (20%)
       No intramammary lymph node tissue9 (18%)
       Intramammary lymph node present1 (2%)
      a In one out of the three patients identified to have an intramammary lymph node in the IMF with no breast tissue, the inframammary node contained metastatic breast cancer.

      3. Discussion

      Evaluation of the inframammary crease and its position is an important aesthetic consideration after breast reconstruction. As mastectomy has become less radical, there is some reluctance to resect the IMF contents routinely as this may lead to poor definition or distortion of the natural inframammary crease, thus adversely affecting aesthetic outcome after immediate breast reconstruction. The traditional description of a total mastectomy includes the viewing of the anterior rectus sheath and external oblique muscle fibres when the inferior mastectomy flap is raised. This is usually only possible if the IMF is opened at the caudal extent of surgical dissection. If the IMF is dissected at mastectomy, extensive undermining of this area should be avoided to maintain the zone of adherence. If the IMF is breached, it must be repaired to reconstitute the natural breast crease at the time of breast reconstruction to maintain the correct breast implant position to achieve an optimal final aesthetic result.
      • Gui G.P.H.
      • Tan S.M.
      • Faliakou E.C.
      • Choy C.
      • A'Hern R.
      • Ward A.
      Immediate breast reconstruction using biodimensional anatomical permanent expander implants: a prospective analysis of outcome and patient satisfaction.
      We have previously shown that primary breast tumours were detected within the IMF in 4/580 patients (0.7%).
      • Behranwala K.A.
      • Gui G.P.H.
      Breast cancer in the inframammary fold: is preserving the inframammary fold during mastectomy justified?.
      Watson and Watson
      • Watson J.R.
      • Watson C.J.
      Carcinoma of the mammary crease: a neglected clinical entity.
      reviewed 402 consecutive cases of breast cancer and found seven cases (1.7 percent) involving the IMF. Haagenson
      • Haagenson C.D.
      Diseases of the breast.
      reviewed his vast breast cancer experience and reported 26 cases involving the fold; as the total number of cases treated was not provided, the proportion of IMF tumours in that series could not be determined. A single case of breast cancer forming in the IMF area after prophylactic mastectomy in a patient with a family history has been described.
      • Cederna J.P.
      Preservation of the inframammary fold: a plea for close follow-up.
      Mammography may be unhelpful in the detection of IMF tumours as this part of the breast is tightly bound down to the chest wall and might not be included in conventional mammographic views.
      • Haagenson C.D.
      Diseases of the breast.
      • Behranwala K.A.
      • Gui G.P.H.
      Breast cancer in the inframammary fold: is preserving the inframammary fold during mastectomy justified?.
      In our study, almost a quarter of the IMF specimens resected contained breast tissue (22%). A surprising finding was that 8% of IMF specimens contained intramammary lymph nodes. The patient with an inframammary lymph node within the IMF involved by malignancy had immediate breast reconstruction using a latissimus dorsi myocutaneous flap and permanent expander implant. All 16 axillary lymph nodes dissected were free of malignancy. Based on the single involved intramammary lymph node within the IMF, the patient received six cycles of 5-flourouracil, epirubicin and cyclophosphamide as adjuvant chemotherapy and was recommended chest wall radiotherapy.
      Schmidt et al.
      • Schmidt W.A.
      • Boudousquie A.C.
      • Vetto J.T.
      • et al.
      Lymph nodes in the human female breast: a review of their detection and significance.
      reported that intramammary lymph nodes could occur in any quadrant of the breast and the pathological involvement of these nodes may influence patient management decisions. Egan et al.
      • Egan R.L.
      • McSweeney M.B.
      Intramammary lymph nodes.
      found intramammary lymph nodes in 28% of mastectomy specimens (n=158) but did not specify their exact location. In that study, metastatic deposits of carcinoma were found in 10% of intramammary nodes, with the positive nodes identified in the same quadrant as the primary tumour in only 50% of cases. In stage II carcinoma, positive intramammary nodes had no effect on prognosis but in patients with stage I disease, those with involved intramammary nodes had poorer prognosis compared to those without. Positive intramammary nodes should be staged as N1 even when the axillary lymph nodes are histologically negative, as positive intramammary lymph nodes are coded as equivalent to positive axillary lymph nodes.
      • Greene F.L.
      • Page D.L.
      • Fleming I.D.
      • Fritz A.G.
      • Balch C.M.
      • Haller D.G.
      • Morrow M.
      American Joint Committee on Cancer (AJCC) cancer staging manual.
      To our knowledge, the presence of lymph nodes within the IMF as intramammary lymph nodes has never been previously reported.
      Our finding that the IMF contained breast tissue and lymph nodes in 28% of specimens, requires consideration to resect the IMF at mastectomy in order to minimise leaving residual breast tissue with potential future malignant risk. Neither body mass index, breast size nor patient age predicted for the presence of breast tissue in the IMF.
      If the IMF tissue is dissected at the time of mastectomy, the anterior and posterior lamella of the superficial fascial system should be reconstructed to optimise aesthetic outcome after immediate breast reconstruction.

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