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Year : 2018  |  Volume : 61  |  Issue : 4  |  Page : 644-646
Catechism (Quiz 2)

Department of Surgical Pathology, Tata Memorial Hospital, Mumbai, Maharashtra, India

Click here for correspondence address and email

Date of Web Publication10-Oct-2018

How to cite this article:
Rekhi B. Catechism (Quiz 2). Indian J Pathol Microbiol 2018;61:644-6

How to cite this URL:
Rekhi B. Catechism (Quiz 2). Indian J Pathol Microbiol [serial online] 2018 [cited 2023 Mar 25];61:644-6. Available from:

   Clinical History Top

A 32-year-old lady presented with an inguinal soft tissue mass. There was no other lesion reported elsewhere in her body.

Her initial biopsy was reported as a spindle cell tumor. Thereafter, she underwent a resection, which was submitted to us for a diagnosis.

   Pathologic Findings Top

Gross findings

A specimen of a left inguinal mass measuring 6.5 cm × 5.5 cm × 4.5 cm was received. It was inked on its external surface and serially sectioned.

On cutting opening, a well-defined lesion was identified, measuring 5.5 cm × 5 cm × 4.5 cm, with a variegated appearance, predominantly composed of solid areas. In addition, there were multiple small cystic areas, the largest measuring 2 cm with areas of hemorrhage [Figure 1]a.
Figure 1

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Microscopic examination

Cellular mesenchymal tumor composed of oval to spindle cells, focally arranged in hemangiopericytomatous growth pattern with variable collagen deposition and few multinucleate giant cells [Figure 1]b and [Figure 1]c. Interspersed were pseudocystic spaces, containing blood. In [Figure 2], cells showed mild-to-moderate nuclear atypia. Mitotic counts were up to 3/10 high power fields, without any atypical form and area of tumor necrosis. [Figure 3] shows the Immunohistochemical staining pattern.
Figure 2

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Figure 3

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(1) What is the diagnosis? (2) What would be the most likely diagnostic immunohistochemical (IHC) stains listed in [Figure 3]a and [Figure 3]b. (3) What would be the risk stratification of this tumor?

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.


Readers are requested to send their answers on the following email mentioning the subject in email as “ Answer to Quiz 2.” Do include your name, affiliation and address below the answer. The answers have to be submitted within 15 days of the online publication date of IJPM. The correct answer will be published in the subsequent issue of IJPM alongwith the list of correct responders.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

   Answer of Catechism (Quiz 1) Top


(1). Phosphaturic mesenchymal tumor. (II) ‘Grungy’ calcification. (III) Serum fibroblastic growth factor (FGF) 23.


Pre-operative fibroblastic growth factor (FGF) 23 was 580.6 RU/ml. Normal range=0- 150 RU/ml.

Histopathologic findings

Cellular spindle cell tumor composed of bland spindle cells with distinct areas showing grungy calcified matrix, along with several osteoclasts and intervening thin walled/”slit-like” blood vessels. There were no mitotic figures, pleomorphic cells or areas of tumor necrosis.

   Discussion Top

Phosphaturic mesenchymal tumor (PMT) is a recently included soft tissue tumor in the current fascicle of the World Health Organization (WHO) classification of tumors of soft tissue and bone, in the category of tumors of uncertain differentiation. It was first described by Weidner and Santa Cruz.[2] It is a distinct neoplasm, mostly occurring in the soft tissues and causes tumor induced osteomalacia (TIO) in affected patients, invariably through production of fibroblastic growth factor (FGF) 23, which leads to renal phosphate wasting resulting in hypophosphatemia. Pre-operative FGF-23 level was elevated in the present case. As a result of the underlying osteomalacia, patients present with history of pain, weakness and fractures, as noted in this case. This tumor frequently occurs in middle-aged adults and presents as a small sized tumor, which requires careful examination, including functional imaging, as similarly observed in this case.[1],[3]

On histopathologic examination a PMT is characterized by rather banal appearing spindle cells, thin-walled, “staghorn-like” branching blood vessels along with a peculiar “grungy” calcification. Variable histopathologic features include myxoid change, cartilage, fibrohistiocytic component pigment deposition and osteoclasts, the latter two features noted in the present case. A vast majority of these tumors are benign. However, rare cases of malignant PMT have been reported. Surgical excision constitutes the treatment mainstay in such cases and relieves the afflicted patients of symptoms related to TIO.[1],[4]

There was an overwhelming response from the readers to Catechism 1 to the extent that even before I could see the online version there was an answer in my inbox. Some of the answers given by various readers are mentioned below-

  1. Diagnosis: Phosphaturic mesenchymal tumor; foreign body reaction to synthetic material used during joint replacement; brown tumour (Giant cell tumour of hyperparathyroidism); Neurofibromatosis associated oncogenic osteomalacia; Skeletal metastasis of carcinoid etc.
  2. Histological feature marked in Fig. A: Smudgy matrix, grungy calcification; haemosiderin laden macrophages, immature new bone formation; nerve bundles; cytoplasmic granules.
  3. Confirmatory investigation: Sestamibi scan for parathyroid adenoma; FGF 23 levels Genetic testing for MEN syndrome - RET gene mutation; IHC for chromogranin; Polarising microscopy.

The winners of Quiz 1 are

  1. Dr Aanchal Kakkar, Assistant Professor, All India Institute of Medical Sciences, New Delhi
  2. Dr Gowripriya G, Sholinganallur (Chennai).

Congratulations to the Winners!

Dr. Ranjan Agrawal, Editor-in-Chief

Case contributed by Dr Bharat Rekhi, Professor, Pathologist, Tata Memorial Hospital, Parel, Mumbai 400012.

   References Top

Folpe A. Phosphaturic mesenchymal tumor. In Fletcher CD, Bridge JA, Hogendoorn PC, Mertens F eds. World Health Organization Classification of Tumours of Soft Tissue and Bone. Lyon: IARC Press, 2013:p.213-14.  Back to cited text no. 1
Weidner N, Santa Cruz D. Phosphaturic mesenchymal tumors. A polymorphous group causing osteomalacia or rickets. Cancer 1987 15; 59: 1442-54.  Back to cited text no. 2
El-Maouche D, Sadowski SM, Papadakis GZ, Guthrie L, Cottle-Delisle C, Merkel R, et al.68 Ga-DOTATATE for Tumor Localization in Tumor-Induced Osteomalacia. J Clin Endocrinol Metab 2016;101:3575-81.  Back to cited text no. 3
Folpe AL, Fanburg-Smith JC, Billings SD, Bisceglia M, Bertoni F, Cho JY, et al. Most osteomalacia-associated mesenchymal tumors are a single histopathologic entity: an analysis of 32 cases and a comprehensive review of the literature. Am J Surg Pathol 2004;28:1-30.  Back to cited text no. 4

Correspondence Address:
Bharat Rekhi
Room Number 818, Department of Surgical Pathology, 8th Floor, Annex Building, Tata Memorial Hospital, Dr E.B. Road, Parel, Mumbai - 400 012, Maharashtra
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/IJPM.IJPM_433_18

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