{'fraction_non_alphanumeric': 0.033065512978986404, 'fraction_numerical': 0.009579728059332509, 'mean_word_length': 5.084586466165414, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Solitary fibrous tumour fluctuating in size with menstrual cycle

Solitary fibrous tumour (SFT) is an uncommon tumour that occurs mainly in the pleura, but has also been reported to involve a wide range of extrapleural sites, including soft tissue. Although SFT shows varying levels of positivity for oestrogen receptor (ER) and progesterone receptor (PgR), there have been no published cases of menstrual cycle affecting the clinical course of SFT. We report the first case, to our knowledge, of a woman with ER/PgR-positive SFT that fluctuated in size with her menstrual cycle. A 32-year-old woman presented with 1-year history of a nodule on her pubic mound. Her medical history included a chocolate cyst on her left ovary and presence of epilepsy. Her family history was unremarkable. On physical examination, the patient was found to have a palpable tumour approximately 30 mm in diameter on her pubic mound (Fig. 1a). The tumour was well-defined, mobile, elastic-soft, and not adherent to the skin. No groin lymph node enlargement was found, and all laboratory results were within normal limits. The patient reported that the tumour would enlarge before menstruation and become painful during menstruation. Confirming this, we found that the tumour enlarged to 45 mm in diameter just before the patient’s menstruation and decreased to 35 mm in diameter between menstruations. Ultrasonography showed abundant blood flow within the tumour (Fig. 1b). Based on the clinical features and the menstruationdependent fluctuation in tumour size, ectopic endometriosis was clinically suspected. Surgical excision was carried out, and the whole tumour was submitted for histopathological study. Numerous thin-walled and branching vessels were present in the tumour, and there were bundles of spindle and ovoid cells (Fig. 2a), with moderately irregular nuclei and scanty amphophilic to eosinophilic cytoplasm. Dilated, staghorn-shaped vessels were present within the bundles, and hyalinization degeneration areas were seen around these vessels and in the interstitium. The tumour was not mitotically active (0 mitoses per 50 high-power fields), did not contain inflammatory cells, and did not have an identifiable fat component. Immunohistochemistry showed the spindle cells to be positive for ER (Fig. 2b), PgR (Fig. 2c), CD34 (Fig. 2d), CD99, and bcl-2 (not shown), but negative for desmin, S100, AE1/AE3, CD31 and smooth muscle actin (not shown). From these histological and immunohistochemical findings, a diagnosis of SFT was made. The clinical presentation of SFT in soft tissue that of a well-circumscribed, subcutaneous mass, which can occasionally be painful. SFT usually presents benign behaviour, but malignant variants have also been described. To our knowledge, other than cutaneous endometriosis, only four cases of skin tumours fluctuating in size associated with menstrual cycle have been described (Table 1), and the four were all hobnail haemanagiomas. In our patient, the tumour cells were strongly positive for ER and PgR. Therefore, we speculate that the metabolic activities of the tumour cells reflect fluctuations in female hormones, which lead to increases in lesional blood flow and tumour size during menstruation.